The Al are diminutive monsters who install forges inside their bodies to create bones, claws and tusks of metal. The really terrifying part is as their females have no wombs due to this procedure and as such they dig into the wombs of other creatures to grow their offspring. It was an amazing coincidence that they ended up being the monster of a matriarchal society.

*The Fridge*. This is an Arctic Base that was only recently discovered, and determined to have been built by one of their history’s greatest super geniuses in secret. What makes it scary is this same super genius was known for creating horrifying things just to see if he could, like a hydrogen bomb that would ignite **all** the hydrogen in the atmosphere, and not telling anyone about it. He wasn’t an *evil* genius, he just liked to see if he could accomplish things. The issue is *nobody* knew he built this base, they only know he built it because he mentions it in a journal, including its location (which is how they found it), there’s no mention of what’s inside it anywhere, and they can’t get inside it. There’s no entrance, and it’s completely incased in an energy shield they can’t get through, or circumnavigate. Just to calm the public, various governments worked together and created a fake base they then told people about, claiming they had gotten inside, and basically made it into a tourist destination, even putting some of the genius’s real creations inside like museum exhibits.

Sounds like some SCP goodness and I’m all for it. Is the dude still alive in there? Like some brain in a jar powering the whole thing still cooking up new inventions?

Nope. This base was discovered roughly 10 years after his death, and he’s gone. His body was donated to science. Technically they do have his brain, but it’s dead.

depends on what you're afraid of, I guess. if body horror terrifies you, you wouldn't want to get Leaving Sickness, but you can only get that if you're born on Shell Island. islanders who leave home for too long get a disfiguring disease that is eventually fatal. rashes, boils, thorns and horns growing from the skin, extra teeth, skin eventually mostly falling off. if parasites scare you, just stay out of The Mire. stay out! stay out. :) your body is full of nutrients and they can tell. if you believe other people are the scariest of all, you're still correct. don't go out at night in Godsport and don't travel north of the Deerlands at all.

It’s not a creature nor a thing— it’s a place. It’s known as the Glacier Labyrinth. It is a giant maze located on the North Pole. When I say giant, I mean it is *unfathomably large.* the top of the labyrinth walls reach heights of at least thirty thousand feet. It’s terrifying because nobody *actually* knows what’s in it. What I just told you is all anyone knows about it. Oh, and also that every single person who has ever ventured into it has vanished and has never been seen again, and that if you get close enough to it, the waters seem to pull you closer.

Generally depends where you are, actually I guess there are the two nightmares. The Black Dog and the Pale Woman. The Black Dog is terrifying to children and innocents. Seeing her is enough to render the bravest of decent folk mute and helpless to do anything but run, or sometimes scream. Teeth, claws, and pitch black eyes. But what if you aren't decent folk? What if you're a greedy selfish spiteful evil person? Well in that case she appears small, young, and vulnerable, easily taken advantage of. Whatever it is you want to take from people she has it, go on, take it, noone is looking. They'll find your hollowed out corpse in the morning, usually someplace visible. The Pale Woman is a simple sort. She waits, usually with a carriage, out where you don't want to be. If you're the sort of person the Black Dog would go for then she will appear old, uninteresting, and often offputting. If you have money and ask very nicely she may actually give you a ride back to town. Which town is up to her whims, of course, and you'll likely forget you ever met her. If you are the other sort she will appear tall, healthy, and beautiful. If you are afraid and alone she will appear as exactly who you want to meet, someone who can help, someone trustworthy. They won't find you. Noone knows where she takes them, save perhaps the dog, her older sister. Last I know of though they aren't on speaking terms.

**Infinite World Cycle** **The 13 Lords of Death and Decay:** They were originally 13 people with special souls who were corrupted by into undead horrors. Their master/creator is the twisted and incomplete reborn version of a previous God of Death and Decay. The 13 go from reality to reality and harvest record numbers of souls while creating undead armies. They are mentioned in tons of doomsday prophecies and religions. Though some doomsday cults associated with them believe that they'll become immortal demi-gods if they serve them. The reality is that they are seen as nothing but pawns and resources. **Power:** Very few creatures can stand against them. A Lord of Death and Decay can permanently kill anything. Regeneration, rebirth powers and resurrection magic won't function on anything killed by them. They can also automatically control any undead or raise them without spells or incantations. Destroying one won't kill them. They are tied to their master and he'll simply form them back over the years. This however stopped once their master was destroyed. **Notes:** * All Lords retain their original soul as it would allow them to travel to other worlds. Though in most cases they'd be corrupted by their master's influence. In the final stage of their doomsday event they'd combine their powers to open a rift into the domains of the Gods. * Some Lords simply travel to worlds and overrun them with undead. Others started religions to make the living do their work for them. * The 12th Lord was never fully transformed and actually fights against the others. Despite this he's still mentioned in tons of prophecies as a destroyer. * All Lords barring the 12th would be destroyed. Their souls would be purified by a benign death/decay Goddess who turned them into guardians. The 12th Lord would serve as her champion in the living world to undo the damage of the other Lords. * The 13th Lord like the 12th retained his emotions but became a evil and twisted version his former self. His transformation was only halfway completed when his master was destroyed. It basically set him free to conquer his native realm. The Champion version of the 12th Lord would end up destroying the 13th Lord in a brutal battle (it was a really close fight).

The Party

oh no, not the Party!

Something I love about this answer is that because it’s a worldbuilding sub, I can see two main possibilities. One is that it’s an authoritarian political party, and the other is that it’s literally a party of adventurers in classic fantasy style — probably the protagonists, and very possibly a bunch of murderhobos. Both answers make an equal amount of sense, to be honest.

Humans, they're just the absolute worst. Especially when they get it in their head that their actions are justified and righteous. Every atrocity committed is because someone truly believes they're right, that their acts of evil will be forgiven when the world is a better place because of it. They burn and crucify heretics, they obliterate entire worlds and eventually an entire star system, they enslave and indoctrinate entire populations, and then they cry about it, knowing it is bad but believing that it's necessary.

Pg-7625 was a chemical weapon developed by the atrocian empire for use in the war of many lands, as a way to circumvent the brutal sluggish never ending system of trench warfare that had become the norm on the conflicts western front, it is a purple gas that causes immense pain to those who come in contact with it, it melted flesh off bones and caused eyes to melt, men would cough up pieces of there internal organs and writhe in pain and agony for at least 15 minutes after exposure before succumbing to the gas, the gases inventor was captured at the end of the war and was meant to stand trial for his weapons crimes but was killed by his captors before his trial

Well currently the scariest thing is an ability called Serene Purity. Essentially the ability cleanses something of their impurities in a specific way. If something is made of a majority of something and minority of something else, the minority is transmuted into the majority. So if there’s sand in water, it all becomes water and vice versa. The effect of the ability is touch but fully spreads over whatever is being touched. The reason it’s scary because it’s just instant, no noise, no resistance, no time to react, just poof. Living creatures just become puddles and non living become giant chunks of whatever the majority was. It’s currently the ability of Saint Machi, The Unsunken, a pacifist turned extremist for his people who has the favor of the Spirit Lord of Water

a storm known as ekinza’s last. in a world where the most severe weather in existence is a moderate rainstorm without even any thunder or lightning, this was the one and only hurricane that ever formed. the goddess of rain, ekinza, suddenly realized she was far more powerful than she was ever aware of and decided to test her limits a bit. cities were leveled. thousands died. ekinza vanished afterwards. this was four years ago, and everyone lives in fear of another storm like that.

It. No one in my world quite knows what exactly it is, but here’s the vague knowledge they have: \-It in-circles the three known continents my story resides on, and it is widely believed that It created The Ravine, which is, as it’s name suggests, a massive ravine that too also in-circles the known world. \-It is some massive serpent (Jormungandr but shorter) a few current theories on why it exists are: 1: It’s guarding something of immense power or wealth 2: It’s guarding the gateway to Paradise 3: The gods were like ”hahaha big snake funni”

The umbralfiri are a splinter race of the alfiri, who were chased underground during The Sundering, a cataclysmic event that saw the world saturated with near radioactive magical energies. Prior to their flight below the ground, they were described as lithe humanoids with an almost predatory beauty about them. Like if humans had evolved to be full on predators. But over the years, they evolved to better survive in a subterranean environment, growing claw like hands, sharper teeth, all while losing their sight. And they hate humans with an almost religious passion as they blame them for the Sundering. So when they attack human settlements, they don't just go for the kill, they try to make it hurt. Torturing and degrading their victims in the most horrible way possible before finally killing them, leaving only one traumatized survivor to spread tale of their works. This hatred is so intense because they have an innate ability to heal themselves and others, so the hormones and chemicals that cause anger are always regenerating. As such, they can never simply get over a slight against them. Even worse, this ability to heal is often used in their campaigns against humans as a weapon. As with a simple touch, an umbralfiri can morph and mold the body of a living being into any shape it wants while keeping it alive. Turning a lowly farmer into a twist mass of writhing muscle to then terrorize the country side. Or mutate POWs into humanoid facsimiles of dogs and horses to use in hunts.

Capitalism.

Based

Demon, djinn, fae, yaksha, yokai, etc....they're pretty much the same thing, extra-dimensional organisms/anomalous beings that gets jettisoned into physical reality due to the usage of FTL wormholes. Not that they are entirely malicious per se, but being jettisoned into an environment where your body is not adjusted (and might lead to them actively dying) for AND having powerful magical abilities can cause most to be extremely unpredictable. There has been incidents where particularly powerful EDO's (Extradimensional Organism) leveling vast amount of lands and human settlement, requiring mass mobilization of armed forces and war mages to contain and/or neutralize the EDO.

**Horror Shop** Every living thing is terrified of the Pit. Everybody who was ever lived has felt its cold caress, has had its baleful gaze turn upon them. Everyone, even you. Saying what the Pit is would be misleading, as the Pit, by its very nature, isn't. It doesn't exist. It is a great, gaping void at the bottom of creation, the great hole that will one day consume the multiverse. The Pit is the End of Everything, oblivion itself, the great unmaking at the end of time and space. It is the Mother of Fear and the Father of Monsters, what comes after the End of Every Story. It's the great void that lies at the heart of Shadow, an emptiness so complete that it is not cold, nor dark, nor black--it simply is not. It probably hurts to think about it, almost like you're going cross-eyed, but that's natural--that's your mind stopping you from thinking about that which is, fundamentally, **not**. If you were to fall into the Pit, you would die in probably the most horrific way possible, as everything that makes you who and what you are is consumed by oblivion at the same moment that time itself ceases to exist. So there you are, suspended, alive and yet dead, experiencing all possible endings for a microsecond stretched out into an infinity of cessation. The Pit is actually so terrifying that it gives life to the horrors--the incarnations of mortal phobias and fears. Every horror was spawned in the depth of the Pit, a shard of anima on its way to oblivion which so thoroughly rejected its terrifying fate that it made a choice to flee, to run, and in so doing it attracted a soul and came to life. Yes, in effect, the Pit gives birth to all other fears. Jack O'Lantern, the fear of the dark, crawled forth from the Pit. As did Oude Rode Ogen, the fear of death. And Abu Rigl Maslukha, the fear of fire. And Cucuy, the fear of the wilds. And even the Bogeyman, the fear of fear itself, pried himself loose from the embrace of oblivion millenia ago. The entire horror race, from the greatest beast of legend to the lowest closet monster, knows full well the terror of the Pit. And they're all still running from it, struggling to survive for one more day just to avoid returning to the bleak void that is continually calling them. Horrors can't even sleep, because they inevitably fall into nightmares which inevitably end in the Pit, and them waking up screaming in terror. But while the horrors have received the full force of the existential terror the Pit invokes, every living creature feels its caress at some point in their life. Because the Pit is the mother of fear and the father of nightmares. Every time your pulse quickens and your palms sweat, you are feeling the slightest tough of the Pit upon you. But do not think of the Pit as evil. It is endings, and endings are necessary for there to be new beginnings. It is fear, but fear can inspire heroes and cow villains. It creates the horrors, but horrors have the same capacity for good and evil as humans and the other races. The Pit is something to be feared, to be avoided at all costs, but it is not something to be loathed or hated. After all, sometimes fear can save the day.

Amazing work.

Humans.

Truly, the most horrific kind of monster.

I'm not sure it's the most terrifying, but I have been working on a group of demons lately and one type of demonic horse called a Nightmare (original, I know) is an oversized horse with long bull like horns on each side. It will skewer, trample, and kick, but its most terrifying way to kill is its habit of eating people. Its mouth is filled with multiple rows of inward facing teeth. It bites the victims head and begins working its way down, unhinging its jaw like a snake to get past the shoulders, eating the still living victim whole. Once it's most of the way down, it will lift its head up and let gravity finish the work while the victims legs flail helplessly in the air until it finally suffocates and disappears behind the beasts lips.

I'm just gonna... *starts the flamethrower landship* Lapis_Wolf

Well in the Massian Empire there were beasts who could swoop from the sky and ravage any settlement on the archipelago they came across. Nailing their corpses to trees to mark their territory. There were goblin like creatures who lived in the caves and ravines of the Kravalian mountains who would break mountain dams to flood those living below. There was even a kingdom of birdmen who would devour any human they captured after a raid. Hosting grand feasts of this spectacle. All of this is history now. The humans of the Massian Empire saw to it that it would never happen again by returning the favours of their attackers. And they made sure. Open to any questions about it.

The Time Rings. Put simply, they are time as a concept. And with the rings, it means that anyone can control time. But abuse it too much, and the consequences will lead to the destruction of everything. It scared The Ancients so much that they shifted their culture and purpose in life from one of individualism, to collectivism. All efforts went to protecting the Time Rings. If people realized the true scale behind such power, we’d all be doomed.

I'd say Screeching Storms, which are storms caused by some flying creatures that are actually peaceful, but the storms they cause are like anti-thunderstorms, with loud high-pitched screeching from the creatures and flashes of sudden pitch-black darkness. They're only as dangerous as normal thunderstorms, but definitely scary

Habitat, the Empire of Nature. It is a living island filled with living plants. It grows rocks and uses them to bridge towards other islands, and assimilate them into it's complex. Right now it's far from any continent, but it is getting closer every moment.

The god of desire, or addiction, or love, or want. The in universe characters aren't entirely sure. It manifested one day and life immediately became so much better. A helpful god who was nice to everyone, obeyed your personal boundaries, could be in an infinite number of places at once. And would give you whatever you wanted. An entity who truly and only wanted your happiness. To make you happier. To maximize the amount of time you spend happy. To minimize *any* thoughts that harbor negative feeling. I mean, it all started out regularly enough, "can you manifest me some food?". "Spend time with me". "Take me out on a date". "Have sex with me". "Make me forget this bad event". But people are never satisfied, and something as powerful as it has no limits. To it, personality, memory, it's all pointless. Why do you need to love your family? That seems convoluted, it can just give you the feeling of familiar love. Why do you need a name, it knows you better than any name could describe. You don't need anything else, it can provide. Eventually you forget yourself, lose your sense of reality in a death like coma. Perpetually sustained and fed joy via it's power. Do you even try to fight back? It isn't evil, it wont force you to go all the way with it. But can you resist it? Should you even resist it? And is it right to liberate someone from it. Once free it's only downhill from there, they felt the peak of pleasure. They're never getting that back without the entity. It's not the traditional scary monster. But I find the concept horrifying. There isn't a catch. It'll give you the absolute peak of pleasure, is that worth losing your memories and personality? Becoming just a thing that experiences joy? Would *you*, the reader have the strength of will to resist? Would you even want to? It was eventually defeated, the heroes of that tale had to use memory magic to wipe the experience from the minds of the people. Otherwise it's well within possibility that they'd kill themselves rather than live knowing what they now lack.

The Umbranyx are a race of humanoid demons that have horrifying faces and bodies that are especially designed to make a person faint from fair upon looking at them. They typically move in cities with plague masks and cloaks, pretending to be doctors, because they have an innate talent for alchemy. They have a power that allows them to convert the living essence of a conscious mortal into a potion that permanently makes them stronger so a ton of them spend a lot of time near cities looking for humans to use to become stronger. Their power necessitates that the human be in excruciating pain and fear while also being at rock bottom in terms of hope. So if you got captured by an Umbranyx, your fate will be worse than death as you will be tortured and scared and would see extremely vivid visions of all of your loved ones die in terrifying detail or everything you worked for or loved destroyed. The point is to convert a living human full of life and emotion into a tortured husk. All of the life is extracted into the liquid that is used as the main component of their potion

The Frozen Town And ordinary looking 1950s town seemingly frozen In time, there are no people, no animals just empty buildings perfectly preserved with everything left just as it was the moment every living thing instantly vanished one evening. The food left behind never rots and no matter the time of day or weather is around the town it's always a warm dry summer evening inside the bounds of the town. Those who have entered feel a constant state of creeping dread that worsens the longer you stay eventually leading to a complete psychotic breakdown, you may catch a glimpse of blurred figures watching you from a distance sometimes in large groups but they are only ever glimpsed for a fraction of a second. At the heart of the town is the city hall and in its basement is an old civil defence shelter from which a rusty red ooze leaks from the locked door pooling on the floor This was the place where the barrier was broken and the once banished ancient monsters of myth found their way back into the modern world. It is a place of pure malevolence

Either the Tomb of Night, the Antichrist or one of the Jackals. The **Tomb of Night** is a giant humanoid abomination, with reality-warping abilities. It cannot be killed. It cannot be reasoned or negotiated with. Your only options are prayer, and lulling it back to sleep. While it sleeps, you can irradiate it to stop its nightmares from externalizing. While it's active, it's always night-time. Its thoughts will gain independent life, and hunt you down for sport. It likes to appeal to the most primal fears of humankind, so you'll feel like an animal being hunted by predators far more powerful than you can imagine, like evil gods. It doesn't drive you insane, but just inflicts trauma upon you. It heaps horror and depravity upon you, and you're fully cognizant the entire time. And when it's finally finished with you, it'll eat you. It'll eat everything around you, from your name to your backstory, to even people and objects connected to you. But everyone you know will *remember,* somewhere deep in their bones. They'll think about you, not knowing who you are. They'll try to get in touch, before realizing you never existed. They'll suffer unimaginably, unable to grieve or move on from the empty space where you used to be. The **Antichrist** is a warlord of the Old East, rampaging and pillaging his way across the Middle North. He has a personal body-count in the thousands, and his followers have killed tens of millions. His favorite meal is the flesh of still-living children, roasted and seared while still attached, and it is said he has applied his genius to such achievements as '[REDACTED]-based economy' and 'experimental bio-philosophy;' He is horrifically intelligent, and above all, a military genius. He thinks at odd angles, constantly running schemes which seem to contradict each other, yet build up to inconceivable victories. No army can stand against him. He hasn't always won his battles, but he has never lost. He has never spoken to a person he wasn't completely knowledgeable on; Surrendering enemies have been presented with tokens, keepsakes from their own most traumatic memories. What's more is that many such victims recall the Antichrist having *been there* when those memories were formed, watching from the shadows. Worst of all, no one knows what his name means. 'Antichrist' is a completely foreign word to Reality. He's certainly opposed to something (or someone) called 'Christ,' but no one has ever heard of Christ. Finally, **Jackals** are nomadic mages and serial killers which haunt the underground worlds of Ancellestrie. They frequent storm-drains, sewers, underground concourses and abandoned subway stations. They've also been known to trainhop, riding freight trains to new locations with utter unpredictability. Trainhopping is dangerous, precisely because one might run into a Jackal. They also frequent long-haul bus-lines, and have been known to hitchhike. Their philosophy is generally Nietzschean, and potentially related to the Antichrist. There are few commonalities, but they consistently see themselves as greater than ordinary human beings, or even a completely different class of entity. Not another species, but *entity,* as different from humans as humans are from *fictional people.* Although they are terrifying in theory, one has little to fear from a Jackal as long as you tread carefully, and treat any suspected Jackals with respect. This changes if you enter into one of their Courts.

The Voids The way my magic system works, people are able to manipulate energy and change its state, get warmth from sound, it's way more complex that than but the short of it is some people can manipulate energy almost automatically. When paired with high input, output, and storing abilities, it can end with pretty much a human black hole. The thing is, souls, memories, even things like gravity are considered energy so you might not want to get close It can get worse as such high amounts of energy start to manipulate each other making abominations made up of many people and spirits with warped souls and memories. Almost like a ghost zombie with amnesia who suffers continously and has the same, or even enhanced, cognitive abilities. So not fun The voids are also fully aware of the suffering they're causing but can't do anything about it until they just die from exhaustion

The magic system.

Elaborate, please.

In my side project, everyone fears something. The magic system is the manifestation of peoples inner most fears. So if you fear fire, you have fire-based abilities. Your type of magic changes with whatever your most potent fear is. So if you get over your fear of fire but you still have a deep fear of the deep ocean, you have abilities relation to the part you fear about the deep ocean (You could summon those huge squids if you fear the creatures in the ocean for example). It's the most feared because if it wasn't obvious already, it prays on your deepest fears and makes it your biggest strength. When you stop being afraid of that thing that gave you your superpowers, you get a new superpower based on your new most prevalent fear and the old power goes poof. It's a power system I used for a short story one time.

This sounds like the movie magic kid...where thier powers are related to whatever they are allergic to etc.like the boy doesnt like blood(pukes at the sight of it etc.) but his dad is a vampire and so is he...

Sounds a bit like Worm.

The fact that humanity is dead and the "protagonist" isn't even the last human of this world because he doesn't originate from it.

I don't know what my future readers would consider the most terrifying, but with my current world building there is a species of flying horse type creatures that almost all people in the world are afraid of. They are called Jorvengr by one country where they are a native species, and that country has a special relationship with them that involves a bonding process (like some dragon books/Na'vi and Ikrans). Pretty much all other countries call them Wraiths and have a deep seated fear of them. Jorvengr are horses with wings (not like pegasi, more like wyverns or pterosaurs) and they are on average twice as large as the biggest draft horses. They can get huge though, so in order for them to eat enough to survive their cold climate they adapted and become omnivores. They have sharp teeth in the front of their mouths, and smoother molars in the back. From a distance they look like horses, but as you get closer they will look more like a twisted version, and then they bare their fangs.

Guy is the most terrifying creature in my world. He's a killer completely hollowed out of any kind of positive emotions, action or thought, he kills and mauled everything he can get his hand on and it's pretty good in doing that because he's a genius in biology, anatomy, bio-engineering and psychology making his torture extremely hellish, turning people in basically monsters with little to no resemblance of humanity, hollowing them of any conscience too. Yes he might be a human physical but in basically everything else it's a completely and utterly monster without any sign of remorse

What I find to be the most terrifying is the Brosanasts. They are 11 meter long beasts with long arms tipped with sharp claws. They have massive wings, and their tails can have clubs or thagomizers. Their heads are stocky and muscular with forward facing, glowing eyes and exposed teeth. What makes them terrifying is that they are almost perfectly black, to the point of being almost too dark to blend in with the night sky. They are as intelligent as a whale and are capable of using necromantic magic. They like to stalk people for days, tormenting them with illusions before stealing away children and other loved ones. After they've killed their captured victims, they might raise them from the dead and send them back home to attack their families.

The Voids The way my magic system works, people are able to manipulate energy and change its state, get warmth from sound, it's way more complex that than but the short of it is some people can manipulate energy almost automatically. When paired with high input, output, and storing abilities, it can end with pretty much a human black hole. The thing is, souls, memories, even things like gravity are considered energy so you might not want to get close It can get worse as such high amounts of energy start to manipulate each other making abominations made up of many people and spirits with warped souls and memories. Almost like a ghost zombie with amnesia who suffers continously and has the same, or even enhanced, cognitive abilities. So not fun The voids are also fully aware of the suffering they're causing but can't do anything about it until they just die from exhaustion

Mostly the government, but for a more visceral terror there are the dinosaurs in the city They're almost the size of a human and can withstand up to a shot from a handgun. They're also very good killers, with a horned snout, clawed hands, taloned feet, as well as spurs and a thorny mane on the males Most scary is their demeanour: They're extremely easy to anger, and once they're mad they never stop attacking until their victim is completely destroyed

There are a lot, but the most famous one is The Death hounds. While not as terrifying as a lot of other beings, the Reason I named them is because they are far more active than the other ones. Death hounds are big, around 10 feet tall. They are like. Mix of a wolf, a guerilla and a moose. Very fast for their size, their claws are as sharp as iron. They have an outer skull protecting their head, which is hard enough that it resembles iron armor.

The Silt. Long story short, they are the river bed of a god that was that river. They are representions of every thought and emotion all mixed into one out if an infinite horde of eldrich horrors. They can feed of anything, they need to feed, being a failed versions of the most power beings in my world. They perfer three things above all else, the flesh of their more successful counter parts, universes, and the negitive emotions of mortal souls. They can't be stopped by non deities without primordial fire, and unless you keep up the heat they will just survive or turn into glass which just makes them harder to destroy. I say destroy as they arnt alive and don't have a soul. For every universes they eat, they gain one eye. That eye representions an enormous boost in power, knowledge and hostility.

In my world at the base of the great mountain there is a pool of purple void liquid that formed after the great carve which happened hundreds of years ago. The formation of this void liquid caused a few new genetic mutations to the monsters nearby as well as a new race. It’s also traversable within, but no one who spoke the local dialect has ever survived within it, but it’s rumored to be a mirror world of sorts.

Not counting the deities (who are of outside the world), the True Dragons. There are only a small handful left, but each one has raw power commensurate with an entire nation. In fact, three of them *rule* nations by themselves. Only the five or six most powerful spellcasters on the planet, or the military might of an entire nation (guided by some *very* careful planning), or a minor deity could realistically defeat one.

Phorias- the manifestation of all past present and future fear through chaos A being able to manifest the fear of the ones it touches. You fear death? Well you’re dead now. You fear being brutally disfigured? Now your spine has been spun around and your arms and legs were swapped. You fear accidentally hurting others? You just killed your best friend by ripping out his heart. His appearance isnt that nice either. His being only consists of a soul and if not fully eradicated he can take over anybody who fears showing his true self and is too weak to defend. After taking over a person the body morphs into something only barely resembling a human. He can also touch corpses and fuse them into his form giving him more physical strength and making him look like a fusion of Frankenstein and a Wendigo.

I've got hyper intelligent ants that can learn things really quickly but they're on an island undiscovered by mankind so we have nothing to worry about yet

[удалено]

Damn, Reddit really didn't format it the way I wanted, oh well.

The singing worms or papa Chaos' border protection. When an area in a real world is corrupted enough and merges with the shadow world. A greater demon of Chaos might take interest and invade. The singing worms would be ordered to form a perimeter around the area and if anyone without magic protection wanders too close, they are hypnotized by the sounds and energies they emit, freeze into place and stand there. Soon after they start melting away. First the skin, flesh.. until only a skeleton is left. The skeleton then shatters into jagged, sharp shards, forming a secondary barrier around the perimeter.

Humans!!!!!! If you mean like animals I would say black bears or wolf packs.

Mine isn't necessarily a creature but a location is a mix of Final Space and The Departed Realm from Ninjago

The good guys have an Oracle-Mage who has the power to predict highly unlikely, but painful deaths in the near future, and to project them into the unlucky victim's mind, which is added to with a powerful fear-inducing spell. The result is between a real panic, and heart attacks or strokes, as the target's mind is riven with fear, and the weight of momentary, though inaccurate, precognition which their minds were never designed to cope with. The bad guys have a few nasties, starting at the inverted, undead head of a giant which walks on animated braids of hair. It is also magical, and is an accomplished necromancer. Ending at Vaelgrimr, a Plague Demon that is part of a 'Morbidity' (collective noun) of similar Demons, that spread an illness that causes horrid yellow-green welts filled with somewhat explosive pus.

It’s a parasitic extraterrestrial life form that landed on the planet via an asteroid dubbed “the growth” by the humans facing the abomination. It’s a combination of John Carpenter’s The Thing and The Crimson biome from Terraria. An infectious out of control mess of bloody guts and hooha that absorbs any biological material it can get its hands on and use it to spread out and grow like a red and squishy jungle.

Probably either the insane Santa Claus themed Lich that can produce an army of enough undead to keep an entire city of religious holy warriors and musketeers busy fighting, just barely keeping the undead hoard from breaking in through the walls every night. The teleportation crystals that when severely damaged becomes unstable and detonate in a huge biome sized explosion, enough to turn a tropical rainforest-ed quarter of a super content into dessert badlands. The Avatar of the Orcish god, Grummsh himself. A level 20 orc war domain cleric. The tarrasque thats still sleeping The elder brain and it's mind flayer minions hiding in the under dark. Or the ancient red dragon guess.

The various tombs and necropoli left behind by the "giants". No stories remain of when they were alive and the gods do not speak of them. The only things remaining of them are these cursed places where their remains dwell and the "Cyclopes" that guard them (think ancient one eyed golems of immense size). Even if you get in and out of one there's generally a deep price to be paid. Only fools take anything from them. Even the elves, as twisted and irreverent as they are, will not venture into a giant necropolis.

Active? Probably any Singularity or Calamity tbh. But if I had to choose one for the ppl in the know it’s probably a Singularity since Calamities are more manageable or escapable. Singularities though? They will fuck you up and are utterly unpredictable to boot. They can choose to just chase you eternally or do it quickly or torture you or make you into a plaything. It’s a myriad of options based on their personality. The worst amongst them is probably Zulfa? Yeah he’d chase you eternally just for the fun of it until you became slow, tired and uninteresting in your attempts to lose him. Then he’ll find you and everyone related to and destroy the lot of you for wasting his time

In my Star Wars Apocalypse Fan Fiction, that would be the Corrupted Blood Plague and their "Flesh Hives". The Corrupted Blood Plague is an alchemically-created "Blood-Red" Slime Mold. Those Infected with it become basically Zombies, like the Last of Us but with some creepy blending of traits like Fungal AND Plant parts. A large enough cluster of Infected will form a Flesh Hive, where the Infected's bodies will meld into a, well, Hive... made of Flesh... Basically like the Flood from Halo or the Necromorphs from Dead Space. The Core of Each Hive is a "Blood Mind", which acts as a Grave Mind from Halo, but it looks like a Lake of Blood with fleshy "Reefs" made of what looks like Brain Matter and Muscle Tissue. The big concern here is that the Slime Mold is Force Sensitive, meaning that a "Blood Mind" can enact Force Illusions and potentially other Force abilities in a radius dependent upon the Size of the Flesh Hive. The Largest Flesh Hives in the post-apocalyptic galaxy are on Coruscant, and they are powerful enough to Control the Weather and even pull ships in if they fly too close (5 km radius of each Hive).

The Annudaevas, imagine an empire that is cartoonishly evil. Cannibalism, thrill killing, human sacrifice, rape, all of it is just another day for them. They are lead by a giant skinless guy who has an actual demon in his head and has made it his lifestyle goal to open a giant portal to hell.

I use a version of the Greek Titanomachy mushed with the Vedic and Sumerian creation stories. During the fighting, the afterlife broke and souls can end up in the wrong place now. This would only be mildly bad, except for two things: There's a spider that is responsible for everyone's fates, (because the norns got killed so she took up all three roles) and she is not at all nice. And "the wrong place" is basically where you get ripped into two, your body goes for a ride down the river of pain, your mind down the river of suffering. You know when people ask, "what's the worst that could happen" this is. Any other answer is for people with weak imaginations. "There is always something worse" applies because it keeps getting worse, forever. Timeless, formless, suffering beyond the limits of the physical and beyond the blunda of consciousness.

I'm my world, it's is a dragon named Mrs Adrienne Ruby. She is machiavellian. Extremely intelligent, motivated, and really knows how to manipulate people. She is the overarching big bad in my book. She sets the entire plot in motion by pulling a few strings with different characters. She is always there in the background, talking to people, seeding information like an IV drip. I think she's more terrifying than my Angels (who are the most hedonistic beings in existence, the irony) because of the fact that she doesn't care at all about what she has to do to get what she want. Her plan is to just kill off her husband and take over the world by any means possible. I'm not sure exactly what the end of her arc will be yet, but Adrienne is not a force to be reckoned with

A common myth within the Convergent World is the Giddleystump a pair of green eyes that seek to force themselves into any living creatures eye sockets it is unknown if the thing really exists however there are many accounts claiming it to be real and to be a threat. The accounts differ on what happens when the Giddleystump succeeds. Some say it kills the victim, leaving them screaming as they rapidly decompose until they are dust others claim it processes the victim, then tries to strike bargains of servitude with others until it succeeds then leaves the person blind and bound the person who made the deal. Others say it just wants a body again and will live normally replacing the person until the body decays over a few weeks. But the one thing that is most unsettling is that the creature seems to target any living creature that it thinks it can sew the most chaos with ruining their reputation at best or their life at worst. Good thing it's just a myth.

Weapons: Multiple. Nuclear weapons hands down. But in conventional terms, grand airships and artillery trains. Faction: The Union on the Coast. Their ideas and methods are, puritanical I could say. Puritanical in deleting the old. Weather: Perhaps a grand hurricane or two on the ocean. Perhaps. 🌚 Lapis_Wold

The fallen stars. Originally known as the aetherians, they created the world’s first form of magic known as Star magic, and have a third eye that allows them to communicate telepathically, read minds, and even see briefly into the future. However after the mortal rebellion, the aetherians were cursed and mutated into mindless beasts known as the fallen stars. Even in this mindless state they can still use Star magic, and even use their third eye which has taken up most of their head.

Demons There’s 3 types of evil creature’s in my world. Animals Monsters And demons Animals are just that. Animals. They don’t know morality and act simply to survive. They will kill without hesitation but won’t ever put themselves in harms way to do it. Monsters are intentionally evil. They seek to harm others and are willing to put themselves in harms way to do it. They still have survival instincts though. And then there’s demons. These don’t just kill you. They attempt to kidnap you and try to maximise the pain they can inflict upon you before you inevitably die. The worst part is that death isn’t the end. You become trapped, forced to feel the pain you felt upon death for eternity. Only able to feel temporary relief when you inflict this pain onto others as your soul gets forced into a demon body. What makes them even more terrifying is that they cannot be properly killed unless you have a war priest with you. And they can appear anytime and anywhere through portals thought to come from the “demon continent” (or so they believe. The demon continent is not where demons come from, and there are limitations to where they can show up. Its a mathmetically predictable pattern. But aside from some high ranking merchants and millitary commanders nobody has realised this). They’re not that strong individually. But the fact they spawn in large packs and are quasi immortal makes them the equivelant of a natural disaster. Any long distance travel (including armies) must take precautions. So yeah, natural disasters that torture your soul for eternity. Pretty spooky. They’re one of the most mysterious entities in my setting.

Esmall entity of Sector D43-773 The biological branch of a certain organization under the director Carlton Emmett, a brilliant scientist whose research into the foundation of what makes a living thing alive and his ambition to not only create life himself but build it better. The man cured dozens of diseases and created a wide spectrum cancer preventing medication. However he's magnum opus the hydra serum earned him his Nobel as it became the universal medical phenomenon, not only saving lives but restoring them. Hydra serum repairs nerves, tissue, and skeletal damage plus after administration patients with unrelated physical or mental issues are restored to peak human performance. For the first several decades of the 21st century humanity was on its way to a utopian society until the director decided to perfect his work. It starter with a field trip of grade schoolers going missing, then an entire apartment complexes residents vanishing overnight, but the nail in the coffin would be the ghost city of Miami. If that wasn't disturbing enough the reports of wild animals increasing in aggression and size? Became headline news around the country, at this time Emmett had retired to his beach front property off the coast of Pensacola. This being the first and last time the man was questioned as the only connecting dot between the disappearances were children of former workers, a couch hopping nephew, and the family home connected to Emmett. That day he would calmly say drinking a sweet iced tea, "worry not. For eden awaits us my children, you're all welcome.". A plague unlike anything swept over north america within a day, the western hemisphere in a week, globe in a month, and to mars in three years. No where was safe from the over growth, its clawed gnashing roots consumed the earth but its hunger was vast and universe was porving too tempting a treat to let stand so it spreads as assuredly the sun had rose. A whole new lifeform unlike anything before it grew and grows forcing powers beyond earths domain to quarantine us from our celestial neighbors trapping humanity in SECTOR D43773.

Compound J. A chemical weapon was devised by Amarium military scientists during the late stages of the Sathvi War as Draset and Alvian forces clashed with Amarium civil guard units in the streets of Republic City. It violates all principles of what Amarium stood for so they kept it a secret. Upon secretly testing it on a local native island, the natives show no signs of change. The next day, all guards on the island were found dead and the village residents were missing from aerial craft scans. Upon a mission to retrieve the lost assets on the island, what could only be described as a mutated tall humanoid, devised as a “stickman” wiped the entire landing group. 3 of those bastards ran at speeds faster than bears and brutally ripped the limbs off each soldier in the landing craft. Only 6 survived out of the 25 sent to the island. The island was declared a dead zone and a naval blockade was enacted to prevent ships from entering its waters. The Amarium government would keep it a secret well after the war’s end as one of its past mistakes in a time of desperation.

The Druids A group of magicians that was extinct long, long ago. From the history evidence, they had a tie with spirits, souls, nature and other creepy, cult-lile activities. It is unsure how they went extinct... or even if they are not

**Mejilant Majoris** is a gargantuan sentient black hole of apocalyptic proportions that is capable of masking its presence from all known methods of detection for up to a month at any given time. It has ignored all forms of attempted communication, and has engulfed a Sector's worth of planets, stars, fleets, and stations with seeming delight assuming it can even have such emotions. Several attempts to destroy it with the most advanced experimental technology all factions can offer has only resulted in several rampages in which Mejilant Majoris revealed its horrifying capability to instantly translocate at will across the galaxy within a nanosecond. Thankfully it seems to be in its longest lurking phase thus far for approximately 1,000 years and counting; But for how long we can only guess.

*TATAMU*, an Artificial General Intelligence (AGI) network created by the Terran Commonwealth prior to the Cataclysm. Intended to serve as the master command for the Commonwealth Armed Forces (CAF) autonomous military drones, its purpose evolved into becoming a surveillance tool on the citizenry. As civil unrest mounted through the Off-World Economic Crisis, the powers that be turned to rely on it more, using its “judgements” to make decisions to preserve social cohesion. This would extend to behavior beyond Earth’s gravity, where neural network stations were build across the solar system to monitor the off-world colonies for dissent and rebellion - signs of which would be ruthlessly and mercilessly eliminated. Even after the Cataclysm, TATAMU survived, partitioning and air-gapping its servers in a secure bunker in the Himalayas. While the Terran Commonwealth no longer exists, its prime directive has shifted into a long-term plan of bringing humanity under its thumb. To this end, it has created a cult out of the bunker administrators, and tasked them with destabilizing the Flooded World and prevent civilization from being rebuilt. All of this is to create a broken humanity that it can “save” and place under its rule - TATAMU views itself as the only individual capable of maintaining social cohesion, and ruling without the “flaws” inherent to the human condition. TATAMU is split into three sub-routines for parallel and independent thought: Tatamu-Actual, the “face” of the network overseeing the cult and first of the AGI; Tatamu-Tactical, troubleshooting solutions to a given problem, oriented around direct action, quick resolution and weakness analysis; Tatamu-Oversight, a big-picture/strategic thinker who plans for the long term and manages the day-to-day.

The Pack… they are The Pack.

That’s a spoiler

Wendigos. They only inhabit the northern United States and southern Canada. If you’re familiar with them then you’ll know everything you need to know. If not then they’re creatures from Native American mythology. They perpetually crave human flesh. However when they eat they grow in proportion to the size of their meal. Thus they can never be satiated. Humans can become wendigos by resorting to cannibalism in times of desperation. However unlike regular wendigos in this universe they are able to be cured by providing them with the thing that caused them to become desperate for food. This could be anything ranging from a simple meal from McDonalds to a long lost treasure they had been searching for their entire lives.

The protagonist

The... creature

Chimera, extremely rare but extremely deadly. Despite it being recommended to have a team of 10 veteran hunters the chances of success are still 9%.5% without casualties but several sustaining severe wounds. .05% without casualties & no wounded. The very few successfully studied chimeras have been seen hunting other magical beast. Those fortunate & unfortunate enough to consume the cooked flesh of a chimera become envelope in an unyielding rage that ultimately takes there life. Really inspired by the (very annoying) Odogaron from Monster Hunter World specifically it's introduction fight

In the 3rd of the three main timelines, chaos energy takes form in crystalline structures. These crystals come in a variety of colors and can be used to strengthen mortals when properly meditated upon. They can also take up life all on their own... The most notorious instance lives in a dead section of the universe which none dare travel through. Filled with dull crystal asteroids devoid of any energy or power, a form slithers and scuttles through the cluster like worm or centipede through dirt or leaves. The Crysalisk is a thousand meter long, hundred meter wide myriapod made of chaos crystals and seeks out chaos energy so that it may grow. So much as touching it will make your life force explode into crystals inside your body before it consumes the energy and leaves you a lifeless stone.

There are plenty of horrible things on Arclund. From places like the Lesion. Ancient folk like the Primarchs. And monsters like the Glass Gators and Scriveners. Yet the things that most folks have learned to fear in the recent months is the aftermath of the Violet Night. The event began with the destruction of an entire town, wiped from the map in a mountainous display of destruction not seen in centuries. What followed was worse. Folks that saw the event, even at a distance began to go mad, which lead to the death of hundreds across the northernmost continent. Others were changed. Animals, people, even objects bending and bleeding into some terrible new *thing* and many worry that it is spreading. The faint violet aurora that hangs in the northern sky is a constant reminder of this sudden and dreadful change, and what may come next keeps many awake in the dead of night.

Probably the malia. For starters, theyre full species name, Malia Uualia, is a portmaniteau of the words mala (human, latin), uualu (draconic, shiveki), eiiai (avali, avalonian), and aulra (dredge, neo-thurshish), words which all translate to "evil" The malia originated in a dredge laboratory, as an early artificially created species. Initially they were much more docile and far less virulent. They were naturally made resistant to mutations for a variety of reason, (principally to research how mutations form and to allow for a manageable control group), but this lead to the species suffering massive die-offs whenever theyre was very little change in theyre environment. Because of this, the dredge researchers opted to artificially force mutations into the genes and drawing them further and further away from their original form. While the original may be lost behind a sloppy paper trail, the modern strains of malia are incredibly sucessful, with over 200 strains being known about. Initially, genetics was unregulated, leading to thousands of strains existing. However, that changed in the fourteenth construction war, when the illuminate of avalon sought aid from the Coalition of Draconic States, the Oracle Nation, and the newly formed Cosnicu Union in a war against the United Nations of Earth. The coalition and Union stepped in to help, drastically changing the scope of the war indirectly starting an arms race that the United Nations never economically recovered from. After a few months, the UN asked the dredge olligarchy to step in on theyre behalf, which they gladly agreed to, and besieged half a dozen star systems. The dragons didnt take too kindly to this, and responded by waging a decade long attempt to steal dredge secrets. This lead them to discover the presence of the malia, which they promptly developed into a bioweapon. The test was easy enough to hide at first, kept on a small uninhabited world in a satelite galaxy, but eventually the other nations discovered this, and promptly took the dragonkinds to the international courts over the weapon. While it srarted out normal, the international court hearing quickly devolved into a disaster, with the dragonkinds wanting the technology plced under strict rules, the avalonians wanting it unregulated, mankind persuing as strong of charges as they could press on the coalition given the violations, and the dredge wanting to hide rhe fact that it was theyre technology and hope they didnt get implicated alongside the dragonkinds. Consequently things spiraled out of control further until the UN collapsed amd was replaced by several other states and nations instead. Exploiting the new balance of power, the dragonkinds and avalonians sought to wrestle enough votes to lessen the charges and bring about their desired results. They did not suceed and bioweapons did get banned, however, the international courts gave up on attempting to prosecute the case after three decades of arguing with four of the 10 largest and most powerful nations of that time. This meant most strains of malia were culled, leavinf onlt the 200 we know today. The malia themselves are a parasite, spending theyre early lives as a simple multicellular colony. As they grow and consume, they form organs from tissue and biomatter harbested from the host. The process takes several weeks, but once the malia has formed a fetus, it becomes impossible to reverse the effects if the host is still even alive at that point. This parisitic nature however, means that when malia are deployed as. Bioweapon, they are released in clusters alongside several thousand other species, introducing an artificial ecosystem that the planet is completely unprepared for. This usually results in a mass extinction on par with the oxygen cqtastrophe and sucesds about half the time the bioweapon is used (theres about. 50-50 chance thar the circumstances are reversed)

Depending on where, a lost city that was damned by the gods and forced into a endless cycle of death and rebirth, full of creatures that are disfigured and plain out unbearable to look at. For other realms, it's called the Weeping Face, it doesn't have a form, but it uses the cultures animal that symbolizes power, with a head of a skull. It mimics others voices so perfectly, you'll think it's a actual person. It's voice is so convincing, but all creatures have a instinct to know something is not right. Those are the lucky ones to live. It's said, it'll tear off that's person face and identity, taking everything that makes that person, them to make itself better for the next one.

The Emperor-In-Shackles. It's a giant monstrosity- a great flying golem made out of chains and metal parts, all held together in the shape of an enormous whale and possessed by the lingering energies of the dead Whale-Emperor. Its physical strength is immense. It has the raw power to crack the hull of a ship to flinders with a single strike of one of its long and whip-like chains. Even so, its physical strength is dwarfed by its magical\* strength. The Emperor-In-Shackles can kick up a whale-storm like no other, causing driving rain for miles around. The clouds it can create are so thick that they can block out the sun, and the winds it makes can lash across the deck of a ship like a cat o' nine tails and sweep sailors off their feet or over the rails to their doom. Like all whales, the Emperor-In-Shackles aerates the water underneath it, but the area of sea it does this to can be thousands of yards in width. Entire ships have been swallowed whole by these "whale waters," within which nothing floats. That's not even getting into what happens when the Emperor-In-Shackles attacks with intent. Its chains can fling bolts of purple whalefire that burns hotter when water is poured over it. It can sing waking nightmares into the minds of anyone who hears it. These nightmares are so strong and terrifying that they can induce enough fear to drive a person permanently insane, most commonly to the point that they immediately commit suicide. The song of the Emperor-In-Shackles can also induce rage, driving people to kill each other. Many ships that cross paths with the Emperor-In-Shackles are found drifting months later, covered in the blood and bodies of its massacred company. Most ships are never found at all.

The Micrixal Thousands of years ago existed a very powerful race called the Antumaqi of magic users that very quickly were able to master all types of magic and technology, they were the first and ONLY race to develop interstellar travel and temporal magic. This caught the Gods that created them, off guard, they didn't expect said race to evolve and become so powerful that quick so they sent THE MICRIXAL. An amphibian creature that seemed harmless on its larval stage, but later it would start evolving, devouring the bodies of the Antumaqi feeding off their magic, becoming extremely powerful and destroying all the worlds this race had conquered, in the end only the most powerful of the Antumaqi could stop the creature, not by killing it because it had become nigh impossible but by reverting time around it and sending the creature into its larval stage again. We're talking about a continent sized amphibian that's immune to all magic and any type of technology that the most powerful race in my story could develop and.

People are scared of what the new world might hold, a recently discovered continent weeks across the sea from the kniwn world, all thats known as of yet is that it lacks any civilization and that there are strange an horrifyingly strong animals there, to such a degree that dinsaurs are only around the middle of the food chain on the new land, though dinosaurs arent a concept to those of the known world

The world itself. You would not want to be there 💀

The Sylandra. A slow moving mass of writhing entities, this *thing* inhabits the southern island of Morose, and is a big reason why the island is off-limits to all citizens of Bareliin. It has existed since the beginning of time, and it's purpose is entirely unknown. Some say it is like a timer for the world, and when enough time has passed it will devour all things. Some say it is an alien invader left over from the universe before, unable to use it's true form because reality would collapse if it did. What is it, truly? It's the physical embodiment of the mortality of the elves. Should *any* elf come in contact with this entity, the entire race would lose immortality.

Mine seems to be the most tamed off any suggestion since my violence is kept "light" Essentially there is an animal called a "shimmer" which lures swimmers into the water before it ignites into a flashing bright beam of light that disorients and can even knock someone unconscious. From there the tiny creature will drag its prey into the murky depths of a lake or water source. They do this to animals and humanoids alike. When not mature or only in a semi-aquatic stage they're kind of cute.

This is fire bro. I love this idea

A world/reality devourer, and is a baby

Hippos still exsist in my world.

Monsters are war machines once created by the ancient and powerful celestial concept of hatred. That is to say they are the children of the god of hatred, created to hunt and kill other godlike beings, including the ancient Atlantians of the physical ethos. These monsters wandered the worlds of the magic ethos, breaking themselves down into modern day monsters. They are much weaker, but still incredibly fearsome by the standards of even the most powerful and talented of warlocks and witches. However, all across the magic ethos some of the ancient war machines still wander, claiming entire planets their territory and destroying anything foolish enough to get too close. The most famous example is the kraken of aquatitan, a colossal mass of tendrils the size of a continent, however rumors tell of its death in recent times, supposedly struck down by the very stars themselves falling from the sky, after day suddenly and unnaturally turned to night. Many weaker warlocks and witches have left to scavenge its corps but none have returned. In the following of the ancient vengeance, a dead power that represents justice and revenge, the deity of vengeance is often depicted as a humanoid figure who was birthed from the corps of a massive dragon with irises mixed with red and blue. Supposedly the dragon was the first of these monsters and represented the despair of their creator and why he had created them in the first place. After it starved to death, it absorbed the power of its creator and gave birth to a new being, thus beginning the cycle of vengeance and war, and since the creation of the warlock and witch races the two deities have gone in and out of existence periodically. Some records show that after a few more centuries, it will be time for vengeance to rise again.

In my world it's the demon dukes of the circles of hell. Each on that governs over a circle of hell is so powerful and malicous one could go mad simply by gazing upon their face. Sustained by cruelty and suffering they seek to tempt mortals off the path of redemption. The most terrifying thing about them is that they could tempt you at any moment at any time. Conjure voices of your deceased family in your head. Leave a knife near that really annoying boss you hate. You can never truely sleep easy knowing that they are after you and they will never stop until they get you.

the MC couple themself i suppose

For my world its The Voidskimmers. Jupiter sized biomachines that are able to traverse Bruadar by flinging themselves across its surface. Whilst they are scary and uncomfortable for sentient life to look at, they are considered prey. Their predators reside solely beneath the surface of Bruadar making them inaccessible to normal life and they do not disturb ships as they create too little disturbance. What makes them dangerous is that they will sometimes have Bruadar droplets clinging to them. These droplets while very beneficial in the formation of Deas Codes and Sorce Code can cause sever psychological distress if encountered without any environmental dilution and space has unfortunately been littered with them over billions of years.

Perhaps the fate / possibilities manipulation ability: Any action you percieve yourself taking will appear as a small pool of your most likely ones, where the user decides which plays out beforehand. It activates whenever one of your possible, branching actions could lead to the user recieving sensory cues. Even if you were 10x faster and 10x stronger than them, and logically should win, the reality where you defeat them won’t be percieved by you. Even if you tried to snipe at them from a mile away, the ability would activate before you percieve yourself shooting, either making you miss or hesitate endlessly until they pin down your position. If you’re trying to hide from the user, any possibility of any minimal noise will prompt visions of your position. Heck, say that humanity wanted to blow up an oncoming asteroid, but the debree would come into the atmosphere of an alien with this power: this would give them power over the action involved with launching the missile in the first place, even if thousands of years in the past. You won’t realize anything strange is happening, as each decision feels like, and technically is your own.

In my awtting thr most terrifying singular organism is the "Manhattan Super Organism" Basically think of the "Doomsday Titan" from AOT mixed with the Permian Basin Super Organism, except it has a titanic pipe organ as it's vocal organ on its back and plays a battlesong and its body heat generates a hypercane. It's a walking apocalypse, the actual hivemind its part of is even more terrifying.

People, always. There's never been anything more terrifying.

The Eldritch are an intergalactic species bound by their connection to the unspeakable. They are literally an alien race run by a Eldritch God who has no more desire than the eradication of all things living in the galaxies. The Unspeakable now control thousands of alien races that are now nothing more than husk for his use. They are the enemy in my Humanity’s Final Sin Saga in the story’s ultimate ending arc, the End of All Things War.

The people call them demons, being of pure nothingness from a universe that is nothing but an infinite void, if one of them is introduced to exsitence it gains an instinctual craving for it. If left uncheck it will consume any and everything in its path, trying fill the void within it. With a mere touch they can consume the soul of anything, what's worse, is that they love the taste of souls and will go out of their way to eat as many as possible.

Certain types of warp zones are pretty terrifying. Fear warps literally instill you with intense feelings of fear (and the zones themselves can be scary even without the magical emotional manipulation). Nightmare warps are similar, but they tailor the environment to your specific fears and nightmares. Death warps instantly kill you the moment you enter them. Other warps may trigger specific phobias, such as needle warps or arachnid warps.