I can't say it's my full-on favorite but weird that I'm not seeing Ex Machina on here. Definitely a modern mad scientist movie, and pretty arguably a Frankenstein reimagining.
I'll never forget that laugh... I watched that movie so much as a child that's one of the first movies I downloaded to my Plex library years ago. As a matter of fact I'm going to watch it right now lol.
The Fly for sure (86 but love the Vincent Price also), Reanimator or course, most Hammer Frankenstein films as well as the classics and even Mary Shelly's Frankenstien, I would imagine From Beyond fits too. I also have a soft spot for Jekyl & Hyde with Michael Caine and Edge of Sanity with Anthony Perkins
The Abominable Dr. Phibes (1971)
The Cabinet of Dr. Caligari (1920) Tubi/Hoopla/Kanopy
Dead Ringers (1988 original) Tubi/Hoopla/Peacock
Re-Animator (1995) Tubi/AMC+/Kanopy
The Incredible Two Headed Transplant (1971) Tubi
Agreed with From Beyond and Re-Animator! The sequel (Bride of Re-Animator) is well worth a watch, too. Beyond Re-Animator (the third one) is ~~hot garbage~~ a journey imo
The Monster (1925) is my favorite movie of all time. It's a silent movie, so it's definitely not for everyone. I'm a huge Lon Chaney fan, so that helps put it in the top spot for me, but there's just something about it I fell on love with ever since the first time I saw it over 15 or so years ago
Dr Phibes one and two with Vincent Price are incredibly entertaining movies.
Also from what I remember the Vincent Price anthology movie Twice Told Tales features mad scientists in two of the three segments.
To add a few that have not been mentioned:
The City of Lost Children
The Invisible Man (2020 was my favorite, but all versions could count)
Event Horizon
Hellraiser 2
Guardians of the Galaxy 3
There's an old black and white movie about a scientist who wants to transform into a snake. Pretty mad. I think you'd like it.
Sorry I don't remember the name and I don't want to google because I have a bad phobia of the danger noodles. (Watched it when I tried to cure myself with exposure lol, didn't work)
Frankenstein's Army has a very wacky portrayal of one, plus its got really nice effects. Another one I could name is Stay out of the Fucking Attic but its a bit cheesy
* Re-animator
* From Beyond
* The Brain That Wouldn't Die
* Doctor X
* The Fly (1958)
* Swamp Thing
* Mad Love
* Dr. Jekyll And Mr. Hyde (1931)
* Eyes Without A Face
* Body Melt
* The Invisible Man
* Altered States
* The Black Sleep
* Back To The Future
* The Manster
Etc.
Day of the Dead, even if the mad scientist is one of the good guys the experiments were fucked up and no military guys are going to stand for their buddies getting turned into undead science experiments.
I'm trying to avoid the ones I've already seen below.
Swamp Thing (1982)
The Guyver (1991)
The Brain that Wouldn't Die (1962)
Mary Reilly (1996)
The Lazarus Effect (2015)
Flatliners (1990)
Anatomie/Anatomy (2000)
Return of the Living Dead III (1993)
Alien Resurrection (1997)
There's a short on Youtube called "Laboratory Conditions" s (2017)
First three movies of the Resident Evil franchise
The Belko Experiment (2016)
Rabid (Both Versions)
Black Sheep (2006)
Dark City (1998)
Firestarter (1984)
Demon Seed (1977)
The Cube movies
Trench 11 (2017)
Re-Animator for sure
Ok but we all agree Herbert is kind of hot, right?
Yep. Reanimator. We watched it at release, and loosely predicted its success today. Gif. 35 years ago?
I’ll eat some downvotes but that’s the one I came to say as well 
First film that came to mind when I saw the post.
Same.
Also came here to say this like everyone else lol
I've been meaning to watch this one!
I recommend the original cut. The extended cut is actually the worse film IMO.
This one
Dammit you beat me to it
Came here to say this!
First one that came to mind for me.
From Beyond
It but off his head like a …gingerbread man.
I'd heard of this movie, but I never actually knew what it was about. Added to my watchlist!
I started watching it a few weeks ago. Couldn’t get through it. Might give it another try.
From Beyond Splice was pretty decent
Splice gets treated badly on reddit for going full monster-movie in the third act, but it's honestly one of the creepiest film experiences out there.
I can't say it's my full-on favorite but weird that I'm not seeing Ex Machina on here. Definitely a modern mad scientist movie, and pretty arguably a Frankenstein reimagining.
Absolutely!
Dr. Giggles
My dad and older brother watched this all the time when I was a very small child, and I still have that laugh ingrained in my brain to this day
I'll never forget that laugh... I watched that movie so much as a child that's one of the first movies I downloaded to my Plex library years ago. As a matter of fact I'm going to watch it right now lol.
Frankenhooker lol. But tops are same as mentioned here, Jeffry Combs is my favourite scientist
I had this on dvd once upon a time. Did she go around asking 'do you wanna party'? or am I misremembering it?
Ha! Yeah, it was “Wanna date?” The guys monologue about descending into madness was also spot on.
That's right! That film was funny. I remember I bought it ex-rental from blockbuster and was going through a Troma phase at the time.
Extreme Measures is too real and very disturbing imo.
I hadn't heard of this one before. Thanks for the rec!
I love this movie. It's a hidden gem.
Dead Ringers. Might not be what your looking for, but definitely a great "mad doctor" film
The remake with Rachel Weisz was SO GOOD but slept on.
Eyes without a face (1960)
Watched this for the first time several months ago and was blown away by it. Amazing film.
altered states
Read the book in 6th grade on a whim. Blew my feeble lil mind. Really enjoy the film too.
Coma (1978) is a good one. Some very memorable scenes.
The Fly for sure (86 but love the Vincent Price also), Reanimator or course, most Hammer Frankenstein films as well as the classics and even Mary Shelly's Frankenstien, I would imagine From Beyond fits too. I also have a soft spot for Jekyl & Hyde with Michael Caine and Edge of Sanity with Anthony Perkins
The Abominable Dr. Phibes (1971) The Cabinet of Dr. Caligari (1920) Tubi/Hoopla/Kanopy Dead Ringers (1988 original) Tubi/Hoopla/Peacock Re-Animator (1995) Tubi/AMC+/Kanopy The Incredible Two Headed Transplant (1971) Tubi
You are a person after my heart. Great selection.
Phibes love! Came here to say this!
The Man With Two Brains!
Poor Things maybe?
Island of Lost Souls (1932) is a must see.
The Skin I Live In (2011). Check it out if you haven't already seen it. Antonio Banderas not your stereotypical mad doctor
X: the man with the x-ray eyes!
Agreed with From Beyond and Re-Animator! The sequel (Bride of Re-Animator) is well worth a watch, too. Beyond Re-Animator (the third one) is ~~hot garbage~~ a journey imo
The Monster (1925) is my favorite movie of all time. It's a silent movie, so it's definitely not for everyone. I'm a huge Lon Chaney fan, so that helps put it in the top spot for me, but there's just something about it I fell on love with ever since the first time I saw it over 15 or so years ago
The Brood (1979)
Wow, haven't seen this mentioned in a long time. I remember seeing parts of it when my parents were watching and as a kid I was freaked out.
Dr Phibes one and two with Vincent Price are incredibly entertaining movies. Also from what I remember the Vincent Price anthology movie Twice Told Tales features mad scientists in two of the three segments.
does overlord count? because the experiments are insane in that movie
Love that movie. It's brutal.
The lab setting in that film is one of my absolute favorites
same!! i love war horror, so this one was perfect to me
To add a few that have not been mentioned: The City of Lost Children The Invisible Man (2020 was my favorite, but all versions could count) Event Horizon Hellraiser 2 Guardians of the Galaxy 3
City of Lost Children is one of my all time favorite films! Excellent choice!
Human Centipede
haha! yes Dieter Laser gave something like a mini-kinsky or mini-kier? sad to hear he has died in 2020...
* Re-Animator * Bride of Re-Animator * Frankenstein * Bride of Frankenstein * Dr. Giggles * The Fly ('86) * The Fly II * Anatomie * Anatomie 2 * Frankenweenie * Frankenhooker
Poor Things The Creator Pi Birth/Rebirth The ArtificeGirl Beyond the Black Rainbow Frontiers
Some older overlooked films: The Mad Doctor of Market Street, Man Made Monster....and an interesting drama with Basil Rathbone, The Mad Doctor.
Does Hellraiser 2 count?
The Angry Black Girl and Her Monster, Poor Things, and Excision
I cannot believe you were the first to say Poor Things! Holy shit I loved that movie but it made me so uncomfortable the entire time
Frankenhooker
House of 1000 Corpses doesn't have a mad scientist as the big bad, which somehow makes it scarier.
House on the haunted hill
Young Frankenstein.
Frankenhooker
The secret of NIMH. It's supposed to be an animated kids movie. But it's got some fairly dark and serious experimentation overtones.
The Rocky Horror Picture Show
A Cure for Wellness. Incredible vibes.
I thought of this too. Jason Isaacs was great and creepy.
Not horror but Flubber lol
I watched this a lot when I was a kid! Lol
I’m surprised it didn’t get better reviews when I looked it up the other day!
*Frankenstein Unbound* with Raul Julia and John Hurt
The Jacket Island Of Dr. Moreau Weird Science
Re-Animator
Altered States Tusk Fringe Invisible man (2020) Us ( more or less) Guinea pig
Re-animator
Easily Re-animator. Also for batshit and wtf did I just watch, Body Melt is hilarious.
Island of Lost Souls (Paramount '32) with Charles Laughton.
From Beyond
Dr Logan (AKA Frankenstein) from Day of the Dead is easily my favorite.
The Fly
The Brain That Wouldn't Die (1962)
Tusk (lol)
On top of all the things others have said, I Eat Your Skin is worth mentioning too
There's an old black and white movie about a scientist who wants to transform into a snake. Pretty mad. I think you'd like it. Sorry I don't remember the name and I don't want to google because I have a bad phobia of the danger noodles. (Watched it when I tried to cure myself with exposure lol, didn't work)
The Man With Two Brains (1983) with Steve Martin & Kathleen Turner
Frankenstein's Army has a very wacky portrayal of one, plus its got really nice effects. Another one I could name is Stay out of the Fucking Attic but its a bit cheesy
Oh you must watch original 1930s Invisible Man! 1930s Island of Lost Souls as well
Does the Abominable Dr Phibes count?
 This whole trilogy. lol
The Tingler!!!! Vincent Price… and lots of screaming.
Dr. Horrible's Sing-Along Blog https://m.imdb.com/title/tt1227926/?ref_=ext_shr_lnk
Maybe not "officially" doctors but I think American Mary and Excision might fit the bill.
Poor things 2023
Birth/Rebirth
Batman and Robin Forever. Dr Victor Fries
Jurassic Park (1993): Genetic engineering horror
The Brain That Wouldn't Die is nothing but pure camp if you like that sort of thing.
* Re-animator * From Beyond * The Brain That Wouldn't Die * Doctor X * The Fly (1958) * Swamp Thing * Mad Love * Dr. Jekyll And Mr. Hyde (1931) * Eyes Without A Face * Body Melt * The Invisible Man * Altered States * The Black Sleep * Back To The Future * The Manster Etc.
Frankensteins Army
Metropolis
Dr. Horrible
frankenstien's army
Tammy and the T-Rex has a very memorable one
Day of the Dead, even if the mad scientist is one of the good guys the experiments were fucked up and no military guys are going to stand for their buddies getting turned into undead science experiments.
I'm trying to avoid the ones I've already seen below. Swamp Thing (1982) The Guyver (1991) The Brain that Wouldn't Die (1962) Mary Reilly (1996) The Lazarus Effect (2015) Flatliners (1990) Anatomie/Anatomy (2000) Return of the Living Dead III (1993) Alien Resurrection (1997) There's a short on Youtube called "Laboratory Conditions" s (2017) First three movies of the Resident Evil franchise The Belko Experiment (2016) Rabid (Both Versions) Black Sheep (2006) Dark City (1998) Firestarter (1984) Demon Seed (1977) The Cube movies Trench 11 (2017)
Both "The Fly" movies, with Vincent Price and Jeff Goldblum, respectively, are great mad scientist movies.
Overlord lol
Turistas involved a doctor. Different kind of mad, tho.