History Main / InvoluntaryShapeshifting

* In ''WesternAnimation/TurningRed'', Mei transforms into a hulking ''10 foot tall'' red panda whenever she exhibits emotional overload, such as [[GenkiGirl uncontrollable joy]] or [[YouWouldntLikeMeWhenImAngry anger]].

* In one episode of ''Series/MysteryScienceTheater3000'', "The Undead", a witch named Lydia (who transforms into a bat in the movie), appears on the Satellite of Love. As she tries to deliver a scary speech to Mike and the 'Bots, she starts shapeshifting into all sorts of things, uncontrollably. "I've never been a football before!" She ends the segment [[AndIMustScream stuck]] as a bottle of drain cleaner. The funniest one is when she very briefly shifts into Pearl Forrester, who looks very confused at her new surroundings.

* In ''Fanfic/WhatTomorrowBrings'', Gafinilan is so surprised to see a guide tree on Earth that he [[ShapeshifterDefaultForm demorphs]] without thinking about it.

* A ''Franchise/DonaldDuck'' comic story by Carl Barks once used a variation where Magica De Spell comes up with a concoction that, after having been sprayed onto somebody's face, would change the victim's face to that of anyone they look at. She naturally plans to use it to blackmail Scrooge to get his dime.

* ComicBook/SpiderMan'': The Lizard is a scientist and friend who periodically transforms into a [[LizardFolk lizard-like humanoid]] by way of the [[HealingFactor experimental regenerative treatment]] he tested on himself, usually triggered by extreme stress. In addition, Spidey himself has had trouble with more spider-like mutations.

* In ''ComicBook/BatmanGothamAdventures'' #58, ComicBook/TheCreeper (Jack Ryder, who in the Franchise/DCAnimatedUniverse was transformed into the Creeper by Joker's laughing gas and toxic waste) is seen involuntarily transforming due to not using the medicine and a bit later mentioning that Creeper has gotten stronger and now only needs a rush of adrenaline to transform even under the medicine. (So he jumps out of the apartment building's window.)
* ''ComicBook/CaptainBritain'': Meggan is capable of transforming in a controlled fashion, but her shapeshifting powers are also linked to her [[TheEmpath empathic powers]] and can cause her to transform based on how others perceive her. Early in life the fear local villagers had of her caused her to take on a more monstrous form, resulting in them fearing her more, and so on. Her "[[ShapeShifterDefaultForm default]]" elf-like form is actually based on what her long-term boyfriend finds attractive.

* ComicBook/GhostRider'': Johnny Blaze used to transform at night. After a while, he would transform whenever there was danger nearby, regardless of the time of day. But eventually, he became able to control it completely.

* In ''ComicBook/CaptainBritain'' Meggan is capable of transforming in a controlled fashion, but her shapeshifting powers are also linked to her [[TheEmpath empathic powers]] and can cause her to transform based on how others perceive her. Early in life the fear local villagers had of her caused her to take on a more monstrous form, resulting in them fearing her more, and so on. Her "[[ShapeShifterDefaultForm default]]" elf-like form is actually based on what her long-term boyfriend finds attractive.
* The Creator/DCComics universe character Man-Bat suffered from this at first. He is a scientist who admires Batman's efforts to stop crime so much that he tries to give himself bat-like powers so he can emulate Batman. He ends up randomly transforming from human to a half-bat form for much of his career, until he discovers drugs which let him control his transformations.

* ComicBook/GhostRider used to transform at night. After a while, he would transform whenever there was danger nearby, regardless of the time of day. But eventually, he became able able to control it completely.
* ''ComicBook/TheIncredibleHulk'': Bruce Banner is the poster child (and {{Trope Namer|s}}) for HulkingOut, due to his transformations being involuntarily triggered by anger or stress. At a couple of different points he becomes more stable, either locked into a particular form for a stretch or able to take control over his emotions to the point that he can mostly suppress or evoke the change as desired. Initially his transformation occurred at night, and later he would transform into his Grey Hulk (AKA Mr. Fixit) form at night, as well.
* Similar to the above, [[ComicBook/SheHulk Jennifer Walters]] initially suffered the same problems turning into the She-Hulk. In fact, she had it worse than Bruce. Bruce had a chance of catching and calming his emotional outburst before the transformation went too far. Jennifer seemed to lack that bit of control, and letting her emotions run too high triggered an unstoppable countdown to her transformation. She later gained the ability to transform at will.
* Franchise/SpiderMan is at times forced to battle The Lizard, a scientist and friend who periodically transforms into a [[LizardFolk lizard-like humanoid]] by way of the [[HealingFactor experimental regenerative treatment]] he tested on himself, usually triggered by extreme stress. In addition, Spidey himself has had trouble with more spider-like mutations.

* ''Series/FraggleRock'' gives us Skenfrith, a one-off EmpathicShapeshifter whose physical appearance changes depending on ''what other people think about him''; it's impressive how upbeat his personality is given this form of being BlessedWithSuck. Red and Wembley like him, think he's very cute and friendly... and that he sports goofy pigtails. Ma Gorg does ''not'' like him, thinks he's creepy and scary for living in her flooded basement, and wonders if he's actually a giant, fanged, two-headed monster. [[ClapYourHandsIfYouBelieve Guess what happens next.]] (Skenfrith: "Aw, I '''hate''' having to be a monster!")

* In ''Literature/TheStrangeCaseOfDoctorJekyllAndMisterHyde'', Jekyll's transformations into his Hyde persona start out voluntary through the use of a chemical concoction. But the more he indulges in his evil urges as Hyde, the more his body considers ''Hyde'' the default form. Eventually he starts changing into Hyde without the chemical. He then needs to take the chemical concoction to return to being Jekyll. And then he runs out of said chemical concotion and finds he cannot make more of it.