- Adventures of the Morning Star: Singed, like in canon League of Legends and Arcane, is a deranged man fueled by his twisted scientific curiosity. He turns people and rats into strange Shimmer monsters that tear apart whoever he or his employer, Silco, order them to.
- In the Arrowverse fanfic To Hell and Back: It's implied Barry dabbled in this while he was a member of the League of Assassins.
Crossover
- Captains Crash (Ducktales 1987 & My Little Pony: Friendship Is Magic): Gyro Gearloose, as per his canon. Launchpad was stranded in Equestria by one of his inventions going wrong.
- Child of the Storm: Has the usual example of Doctor Arnim Zola, an AI in (usually) an LMD version of his original body, which as the Head of HYDRA, Lucius Malfoy, observes, makes him look harmless, even contemptible. As Lucius inwardly notes, this is also very much a mistaken impression; Zola's brilliant enough to perfect Extremis, turning it from its MCU variant (superhuman abilities and Healing Factor in exchange for literally explosive volatility) to its 616 variant (able to grant any superpower within ill-defined power limits), and use Jane Foster's research to build a "Nexus Engine" (giant teleporter) for HYDRA's massive vibranium hulled Helicarrier, the Dreadnought — which he can control, all by himself.
- And he learned from Sinister, who is demonstrated to have technology that can hide him from Heimdall, teleport through/manipulate dimensions, to have mastered human cloning, and even hide from Doctor Strange — though that's indicated to be through someone else's assistance.
- Doctor Reynolds in the Smallville arc of the sequel, who approaches this from an alchemists perspective, seeking (and succeeding) in combining science and magic to create what would essentially be distilled magic, which could be taken in liquid form (since magic and life-force are pretty much the same thing, it would boost the drinker's health and immune system). Unfortunately, he starts using Black Magic and darker Sympathetic Magic to get it by draining Clark, though his journal all but states that Clark isn't the first, and several test subjects died. Since Evil Is Not a Toy, this results in severe Sanity Slippage and an unusual case of This Is Your Brain on Evil (he knows he's gone zooming over the Moral Event Horizon, he just doesn't care).
- Dungeon Keeper Ami: Invoked. Ami's favorite running gag is dressing up in a white lab coat, flipping a large power switch and laughing maniacally; all in good fun.
- Game of Touhou (A Song of Ice and Fire & Touhou Project): Eirin, later, Hisataka Nou, has developed a serum that turns humans into war beasts when searching for a potion of immortality.
- Mythos Effect (CthulhuTech & Mass Effect): Features Herbert West (of Re-Animator fame) employed by the New Earth Federation and actively encouraged in his obscene work. In his one scene so far, he's dissecting a Turian corpse and describing every way he can improve biological weapons to use against them, all with a smile on his face.
- Seventh Endmost Vision has Dr. Lucrecia Valentine, who is a sedate version of this trope, one oriented not around wild scientific discoveries, but around efficiency. A glimpse of her laboratories in Shinra HQ reveal the fundamental difference between her and her canon counterpart, Dr. Hojo; her laboratories actually give the best pay and best hours in Shinra, and it's all focused on incremental improvements which give a guaranteed return. Her calmness in this regard seems to have paid off for her; she's become the fic's equivalent of Weiss the Immaculate, all through her own efforts, making her tremendously dangerous.
- Fallout: Equestria (Fallout & My Little Pony: Friendship Is Magic): Twilight also became an amoral Mad Scientist, torturing and killing countless zebra war prisoners and pony political dissidents and subjecting Discord to a Fate Worse than Death in an attempt to create a serum that would transform normal ponies into alicorns. She pays for her misdeeds when her serum manages to mutate Trixie into an Eldritch Abomination that promptly devours her and absorbs her mind.
Godzilla / King Kong / MonsterVerse
- Abraxas (Hrodvitnon): Alan Jonah and his aptly-named Basement Club cross into this territory with their experimentation on San's old head in the bowels of their Elaborate Underground Base's lower-levels, even performing experiments on humans. Meanwhile, Mariko is a Reluctant Mad Scientist who doesn't enjoy working for Jonah's paramilitary, and she certainly doesn't enjoy being forced to oversee the barbaric experiments being conducted on San and Vivienne Graham.
- Brutal Harry
: Hermione's uncle George Granger's reaction to being told that magic exists is mad laughter followed by shouting "THERE WILL BE! SO MUCH SCIENCE!" - In False Pretences Priscilla Doge makes some aquatic-themed physical modifications to a seventh-year student and keeps him in an aquarium tank in her trunk.Priscilla: Transfiguration as a subject has been stagnant for nearly two hundred years. My colleagues have grown complacent and refuse to push the boundaries because of self-imposed restrictions, rules, ethics concerns. I've been doing something all of them are too scared to be doing, and my research will revolutionise human Transfiguration as we know it!
- Becoming a True Invader: In addition to Zim, there's his old Vortian colleague Crax, who even he thinks is crazy.
- For the Glory of Irk has Professor Membrane (as per canon) and his new wife Moira. From gifting their son hypercubes that be used for both storage and combat, to weaponizing animals as ammunition for cannons, they will never let morality or common sense stop them from doing things For Science!.
- It's very common to portray Twilight as a completely bonkers Mad Scientist in fan works, though whether or not she is good or evil varies wildly: Steamquestria's Twilight embodies every single mad scientist quirk there is but is still quite nice, loving, and caring (except for one time she "accidentally" made Spike 50ft tall and "accidentally" programmed him to destroy the city), while PONY.MOV's Twilight is only slightly less evil than Discord and Wolflor.
- Ask Brainy Twilight: In an odd play on this trope, she struggled with admitting she was one of these until she made a sapient flaming chainsword for a friend.
- Ask Researcher Twilight: Although it's more Grimdark sprinkled with Black Comedy. Twilight has gone completely insane, and is hiding from the government after attepting to vivisect Celestia.
- Contraptionology!: The story centers around Ponyville being struck by a collective fit of mad science mania and turning into horror movie-style cackling, megalomaniac mad scientists obsessed with grand scientific visions and crushing their opponents underhoof as they blaze into a bright, bold future. Each character focuses on a specific project and homes in on a different area of mad science as a result:
- Applejack decides to refine her usual cider-distillation process by working her cider still and most of the farm machinery she had handy into a miniature particle accelerator, under the reasoning that, if regular cider strips away inhibitions to reveal a person's true personality, then "large hadron cider" created by smashing its component yeast and sugar into subatomic particles must be something truly revelatory.
- Fluttershy concludes that the best way to make new animal friends is to make new animal friends, which she does by using an improvised engine to mix butterfly, bee and bat genetic material into a sort of slurry that she then pumps into cocoons, where it incubates until it hatches into a swarm of physically mismatched hybrids.
- Rarity builds a complicated array of metal, giant glass lenses and a huge diamond perched on the roof of her boutique, which she refers to as the Wondrous Lanthorn and powers by burning a tremendous amount of gems. It works as a telekinesis amplifier by effectively reducing the mass of a selected object to zero and firing it at near-light speeds to any desired location.
- Twilight goes the fully transhumanist route and decides to upload her mind into a shapeshifting, immortal liquid metal body in order to transcend the limitations of the mortal flesh. In the process, Spike ends up regressing into a shuffling Igor-like minion.
- By the climax of the story, having the entire town transform into megalomaniacal, visionary and paranoid science people turns Ponyville into a warzone. Functionally every house is turned first into an improvised laboratory and then into a fortified bunker as the overly-crowded mad scientists turn on each other in an all-against-all clash of death rays, fire, ice, weaponized music and magical mass accelerators while war zeppelins, robots and genetic hybrids fight overhead, rendering everything that is not a highly built-over mad science palace into a scorched wasteland.
- Equestria: A History Revealed: King Sombra was said to have initially been a normal king, with a love of scholarly pursuits. When he stumbles upon dark magic, he still takes a very scholarly, scientific approach, dutifully recording his observations, before he starts to lose his mind. Even when he performs his dark magic experiments, according to the questionable Lemony Narrator, he still felt the need to publish the results of his evil experiments with the rest of the world as a continuation of his science-loving side, and possibly his need for peer-review.
- Great Minds Think Alike: Two of the future villains who time-travelled to the past to defeat Twilight on her coronation day are mad scientists of different sorts. Voyager is an insane cyborg transequine who considers her unnatural melding of flesh and machine to be the next step of equine evolution, intends to force it on Equestria over any objections to her plans, and has an extremely self-important personality and tendency towards gloating and angry ranting. Diachrony is a studiously mundane social scientist, whose plan is to assassinate Twilight and throw society into chaos in order to have interesting social trends and upheavals to study."You're a mad... sociologist?" she asked.
A few guards snickered and Diachrony bristled. "As I've said before, Milady," he said testily, "my science may involve studying ponies and critical reasoning with fuzzy data rather than brute-forcing equations and banging atoms together, but that hardly means I'm not a legitimate mad scientist!" - The Mare Who Once Lived On The Moon: Pinkie Pie gets this. While titled 'TESLA' for some Fun with Acronyms, she does have a worrying enthusiasm for the then-new discoveries of atomic science. And is entirely insane.
- Twilight again ends up in this territory too. Shining Armour has to remind her that some of her plans, innocent to begin with, don't need much to turn into devastating weapons. "You don't mean to but, Twilight, there's stuff here that could change the world, and for a lot of ponies and horses and zebras it wouldn't be for the better."
- Oversaturated World: Group Precipitation: "Mad Scientist's Best Friend, by Eon Aon and Fo ME": Talking about Twilight Sparkle's dog, making Twilight herself a mad scientist.
- In Tealove's Steamy Adventure, Baron Zeppeli is studying eye colors, of all things. He kidnaps Tealove so he can forcibly change her color. His lab assistants are a pair of unicorns, Cherry Pie and Waterfire, who constantly bicker with each other.
- Mad Scientists Anonymous plays with the idea that Dr Nambu along with all the iterations from Battle of the Planets, G-Force: Guardians of Space, ''Eagle Riders" and the OAV version were all "as mad as a box of frogs," and sent them to a meeting of the eponymous support group. It goes about as well as you might expect.
- Wilhuff Tarkin, Hero of the Rebellion has a few examples:
- Raith Sienar is portrayed as an extremely intelligence but morally challenged Gadgeteer Genius, whose main issue with the Imperial Navy deciding to put in mass production the TIE Fighter as it is when it was simply a stripped down and somewhat cramped prototype supposed to simply demonstrate the SIE-TIE's engine potential isn't that it will cost numerous pilot lives, but that it would make him appear a hack fighter designer. And when he finds out one of his ideas will be developed in the Death Star, he doesn't really appreciate but considers that the main engineer is competent a boon. The narration points out that Sienar's loose morals (as long as they don't mess with common sense) are why he's still friends with Wilhuff Tarkin.
- The head designers of the Death Star are this, in their own ways:
- Orson Krennic (project director and main engineer) doesn't really care of the destruction it will cause, only to have his name remembered in history for building the Death Star.
- Galen Erso was forced in... And sabotaged the station so it's vulnerable to a fighter attack, knowing that almost two million people will die, to protect his daughter and avenge his wife. He's also quite giddy when Qwi Xux' team speeds up his job by years, and when Tarkin admits his true allegiances and declares that less than two million dead are a small revenge for being separated by their child he admits they were collateral damage to his real goals (Krennic and Tarkin himself).
- While in Legends she was naive enough to not know the real use of her inventions, here Qwi Xux knows what the Death Star is going to be used for... And still actively collaborates.
- As of this writing Umak Leth and Bevel Lemelisk haven't received characterization yet, but they too don't care about.
Unsorted
- Transformers Meta: Wheeljack reprises his traditional role as this. Appropriately, he has pulled some pretty crazy stunts, and has invented some pretty implausible things, like grenades on a sword.
- Rise of the Chosen: In this Mega Man ZX fanfic, the OC Lateral is the Guardians' resident scientist. 99-percent nutter and 1-percent rational, the people who can put up with her eccentric and scatterbrained personality can be counted on one hand.
- Twilight Sparkle in Pages Of Harmony is very much this, having an entire multi-roomed laboratory to extract the genetic essence of the Elements of Harmony from her friends.
- Virgo Zodiarts/Tachibana/Kunieru Emoto in Horseshoes and Hand Grenades who has not only been treating Sonada and Kijima with Cosmic Energy injections so that they can bring back their lost Horoscopes powers, he also transformed Ryusei into a brainwashed cyborg for reasons still not yet explained.
- In Altered Histories Harry sees a goblin healer called Fangcutter who wears a bloodstained lab coat and possesses some rather dubious instruments, cuts Harry's skull open to remove the scar Horcrux while he's conscious and performs unspecified "experiments" after Harry's finally unconscious due to another medical procedure.
- The Cadanceverse version of Carrot Top is a comedic mad scientist, always seeking new improvements in farming and food development, usually with hilarious results when things go wrong.
- Eugenesis explicitly labels the Guardian droids, each of which has an annoying tendency to be ludicrously overpowered and liable to turn on its creators on a dime, as the creations of Wheeljack.
- The Reactsverse:
- Lucina Reacts: Miriel, in contrast to canon. Among the things she's invented for Ylisse are the steam engine, a device that destroys the clothes of everyone nearby, and a dream-walking device.
- Weiss Reacts: Professor Faust tinkers with dark magic and eldritch monsters for... whatever she actually plans on using them on.
- In Coveralls, Scully is a lot more unhinged than in canon, owning a "knife office", enthusing about lethal poison, and killing a man unprovoked. She also wants to get back to her "scientific achievements".
- Harry and the Shipgirls has Abyssal Research Princess. Experiments on her own subjects, has canonically grafted Abyssal parts onto humans, and planted multiple flesh tumors in the members of her own fleet, making it rather difficult to kill her. Being an Expy of Josef Mengele from the Real Live section, she plays this trope dead seriously.
- That being said, not all of her experiments have worked. She once tried creating Abyssal clones of shipgirls. They were such good clones that they turned on her.
- A Flower's Touch: One chapter covers Aerith's life in the labs under Hojo's care in all its horrific, gory detail.
