Shapeshifting Failure is when a shapeshifter can't keep one shape or loses some of their ability. This can be due to illness, injury, age, exhaustion, biological or chemical agents, anti-magic fields and the like. Distinct from Glamour Failure in that it doesn't involve glamours, psychic powers or illusion, their very body is in trouble.
Can lead to Shapeshifter Default Form if they lose control of their power, Shapeshifter Swan Song if they are dying, or This Was His True Form once they are dead. Mode Lock can result if they are forced into one shape and prevented from transforming. Several of the entries in Glamour Failure would be better placed under this trope.
Compare Game Face, where they have dropped their disguise on purpose. See also Morphic Resonance, when even in another form, a character has some traits that give away who they really are, although this is more a limitation than an outright shapeshifting failure.
- In Pleasant Goat and Big Big Wolf: Mighty Little Defenders episode 28, Wolfram creates more mud golems to pretend to be him than he can take, which leads to some of the golems being unable to completely hold their shape. One of them has bunny ears, one of them has Master Paopao's head, a few of them outright have glitchy-looking features...
- The episode "Flicker" has Lamput doused in a chemical that causes him to flip through every color except his trademark orange, thus leaving his transformations utterly worthless. He eventually finds himself in a city street loaded with neon signs and flashy street performers, letting him blend in until the serum wears off.
- The episode "Evolution" has Lamput growing ashamed of his pudgy body after being mocked for it while at the beach. Seeing others with different body styles causes him to piece-by-piece morph his body to conform to others. Eventually, giving himself a muscular form wears himself out too much, leaving him immobile.
- In Pokémon: The Series, Ash and friends met a trainer named Duplica who has a Ditto which can't transform its face along with the rest of it. Team Rocket captured this Ditto and forced it to change its face using threats and punishment and, in the end, when Ash and his crew rescued Ditto, he finally can shapeshift completely into other Pokémon.
- They would later meet Duplica again in Johto, but this team, she has a new Ditto which smaller than her first one. The mini Ditto can transform only into mini versions of other Pokémon.
- Dungeon Keeper Ami: Chapter 126: Arranging Transportation: Breaking a Youma's glamour through the application of pain:
"How do you make a youma revert back to her true form when she refuses to?"
"Oh, that's easy,"
(a ripple of force slammed into the Ami-lookalike, lifting her off her feet and hurling her toward the wall at breakneck speed)
"Ow! Ouch!" Tiger groaned as she glowered at them from the ground. She now looked somewhat like Ami would if she gained a head in height, sprouted short horns, took up body building, and developed a strange skin condition. The black-striped youma whose school uniform now strained at the seams pulled herself to her feet and rubbed the back of her head. "You are no fun at all!"
- Camilo in Encanto has the gift of shapeshifting, and while he's pretty good at controlling it himself, getting startled or physically shocked can cause him to shapeshift uncontrollably. During one scene at a dinner, he shifts rapidly between various forms and ends up getting his face stuck with Fish Eyes and a slack jaw; his father has to tell him, "Fix your face!"
- Moana has one scene in which the demigod Maui retrieves his magic hook from Tamatoa, which allows him to shapeshift again. Unfortunately, he's been out of practice for hundreds of years, so when he tries to use it, he can't quite manage to achieve the form he wants.
- A Mangalore from The Fifth Element shows strain while trying to keep human shape, even before the scanner detects him as non-human.
- Marvel Cinematic Universe: In Avengers: Infinity War, Hulk has grown tired of only being used by Banner as a weapon and refuses to "come out" when Banner tries to Hulk Out later in the movie.
- Terminator 2: Judgment Day had deleted scenes showing that after being frozen, shattered, and reforming, the T-1000 had difficulty keeping shape, showing effects like unintentionally mimicking surfaces and loss of rigidity. In the theatrical version, this was cut down to one scene of its human form briefly turning to its silvery default form.
- The Thing: The team stumbles onto the Thing before it could complete its assimilation of one of them. Thus, when they confront it, it looks just like him except with grotesquely inhuman hands.
- Mystique from X-Men briefly reveals her yellow eyes while in pain.
- Some morphers are allergic to the DNA of some animals, which may cause them to morph uncontrollably. In Rachel's case, acquiring a crocodile nearly collapsed her house when she started morphing to elephant. The problem sorted itself out via a process called "hereth illint", which translates to "burping DNA", and in which the acquired DNA is purged from the bloodstream and manifests as the actual animal.
- When under severe stress, it's possible to lose control over the morphing process. Marco found out that his widowed dad remarrying (his mother is actually still alive, but as Visser One's host) affected him more than he thought when he starts getting into morphs like gorilla-trout, spider-skunk and polar bear-poodle.
- Deltora Quest features Ols, shapeshifters that serve the Shadow Lord and able to take the form of any living creature and in rare cases inanimate objects. There is however a way of testing of someone is an Ol. Level 1 and 2 Ols are only able to hold the same form for three days. Upon this day they will lose control of the form and their bodies start distorting in a phenomena known as "the Tremor", before the Ol retains control of the form and returns to normal. This is exploited by La Résistance, who immediately imprison all visitors to their bases and keep them under constant close surveillance for three days, watching closely for the Tremor to make sure they're not Ol spies sent by the Shadow Lord.
- During Simon the Devious' return in What We Do in the Shadows (2019), he once again tries to steal Laslow's cursed hat and during the ensuing fight, the two become bats. However, Simon reverts on top of a grate, and due to the hat's curse, the transformation process was screwed up and his foot is painfully fused with the metal.
- Metroid: Intelligent beings like humans in Metroid Fusion or Chozo in Metroid Dread give the X Parasites problems when trying to mimic them, resulting in a blob-zombie loosely resembling the infected. The more problematic X are the ones that get it right; one infected Mawkin Chozo brought an end to the Mawkin tribe and eventually all of Planet ZDR, and an infected human scientist nearly killed Samus by trying to self-destruct the B.S.L. station. And that's not even getting started on the SA-X.
- Pokémon: Ditto, a species of Pokémon normally resembling pink blobs and most notable for their ability to shapeshift into anything, are sometimes depicted as having certain weaknesses or tells to their otherwise flawless ability to change forms. A common one in the anime and card game is that Ditto, either all Ditto or only certain individuals, cannot transform their faces. In addition, the Silver and Soul Silver Pokédexes state that a transformed Ditto cannot maintain its form if it starts laughing, which will force it to revert into its default shape.
- [PROTOTYPE]: Alex Mercer loses some of his shapeshifting abilities when infected with a weaponized parasite; while he can still mimic other human beings, he can't shape his limbs into weapons while afflicted.
- Red Alert 3: Spies and Sudden Transports can disguise themselves as an enemy or allied infantry/vehicle unit respectively, which is utterly undetectable without a dog/bear/drone nearby to cancel the disguise. This trope comes into play when they disguise themselves as something impossible, like a plane on land or a land unit at sea (there's only a handful of amphibious infantry units, and dolphins shouldn't be on land). Played for Laughs in one Uprising mission, where disguising a transport as a Soviet Dreadnought and moving to land gets the question "Why is one of our ships on land?" from a confused Conscript and nothing else, even when the "ship" is picked up by a helicopter.
- The Shapeshifting Detective:
- The eponymous main character can transform into anyone they've met so far, a normally infallible ability. However, Sam initially has trouble replicating Poe's voice, resulting in their first words in the new disguise coming out in the Voice of the Legion as they struggle to adjust their tone.
- If you attempt to get answers out of Zak by approaching him as Lexie, he'll offer you a drink as he tries to rope you into a late night photography session. Unfortunately, the drink is spiked, and the drugs result in you quickly losing control of your powers and reverting - not to the Sam persona, but to your true form, much to Zak's horror.
- Awful Hospital: During combat, Jay has the ability to erupt into a thicket of Slob tentacles. It's unclear whether it's at-will, though it likely isn't since he has no memory of doing so afterward, rationalizing the extreme damage the attack causes as "not knowing his own strength". Also, as an Absolute Xenophobe he'd be horrified if he ever realized he might be anything other than human. This trope comes into play because every time he uses the attack, it significantly shortens the time left before he slobbifies permanently.
- DHS Comix: Shapeshifters can only stay transformed for a few hours before they have to change back to their default form; staying transformed for longer than this makes them ill. Of note is that shapeshifters can have any form they choose, while other kinds of shape changes (Mimic's, Were's, Felimara) have only one to three alternative forms, but no apparent time limit.
- my life with fel has a squid hybrid girl pass out from exhaustion due to holding a human appearance too long.
- SCP Foundation: SCP-7955 is a shapeshifter lumbered with a rapidly progressing case of dementia. Consequently, he tends to make some pretty revealing mistakes while trying to disguise himself, from furniture made of meat to people wearing exoskeletons instead of clothing. At one point, he attempts to smuggle himself out of his cell by disguising himself as one of the books he'd borrowed... but is easily given away by the fact that the "book" has no pages, and its author's name is rendered as "Daniel Steal."
- American Dragon: Jake Long: On occasion, Jake involuntarily reverts to his human form, rendering him unable to use his dragon powers.
- In the pilot episode Old School Training, where he is still learning to control his powers, he fully reverts while in flight. Twice in the same episode only his legs change back, revealing his Goofy Print Underwear.
- In Dragon Breath he mistakenly drinks a Power Nullifier meant for his enemy, which forces him into human form.
- More generally, sphinx hair can force dragons into their human forms.
- In Ben 10, there are certain environmental factors which will effect the Omnitrix and cause Ben to be restricted to certain aliens, Mode Locking him in one particular alien, or turning him into a freaky hybrid of two or more aliens.
- The Fairly OddParents! has the episode "The Gland Plan", where Cosmo's "faggigly gland", the organ fairies have that regulates their shapeshifting, breaks down and he needs a transplant from Anti-Cosmo to live.
- Steven Universe:
- In "An Indirect Kiss", Amethyst cracks her gem and nearly dies, shapeshifting sporadically before getting healed.
- In "Steven's Birthday", Steven, realizing he hasn't grown in several years, uses shapeshifting to make himself taller. He struggles to retain the form, which ultimately backfires and turns him back into a baby. He recovers by the next morning.
- In "Back to the Moon", Amethyst shapeshifts and pretends to be Jasper, but she can't keep up her shapeshifting and reverts back, blowing her cover.
- In "So Many Birthdays", Steven, disappointed after failing to throw birthday parties for the Gems, begins shapeshifting and aging to match his emotional state, at one point aging up to an old man. The Gems realize this and manage help him turn back to his usual form by the end of the episode.