Shapeshifter Swan Song

"Stop it, stop it, turn them off! I can't control it! I can't be all of them, not all at once!"

—Clayface, Batman: The Animated Series

Shapeshifters are showoffs. Even the insidious infiltrators like to use their abilities to inspire awe and fear. It's no surprise then that dying is no exception. When a shapeshifter bites the dust they have a veritable swan song of shape shifting as they slide through every single shape they've stolen throughout the episode or movie. Much like the life flashing before your eyes thing, may be considered a realistic survival reflex.

It'll also happen if their powers are short circuited, they're critically injured or KO'd. After their swan song they'll settle into their original form and body, often to the surprise of everyone else, especially if said form isn't human. Someone will usually go "This Was His True Form", and look suitably mournful if it was a friend they lost to The Virus. If the purpose of the swan song is to inform the audience who the shapeshifter posed as (and that they were, in fact, a shapeshifter) this becomes a case of Viewers are Morons.

In shows aimed towards kids or ones where especially Genre Savvy, expect the shapeshifter to possibly survive, thus rendering this trope a bit confusing as the viewer wonders why there's the equivalent of death convulsions going on for a character who will later turn out to be fine.

A special case of Superpower Meltdown. May happen to a Clipped-Wing Angel. See also Shapeshifter Mashup. No Immortal Inertia is similar but for immortals.

As a Death Trope, Spoilers ahead may be unmarked. Beware.

Examples of Shapeshifter Swan Song include:

Anime and Manga

In the Ranma ½ anime, one-shot villain Copycat Ken's breakdown resembles this.
In Kinnikuman, this is how the Choujin King 100 Ton is defeated. 100 Ton uses cue cards in order to take different shapes, but when Kinnikuman throws all of the cards into the ring, 100 Ton starts to reflexively transform into every form at once, making his body unstable enough for his opponent, Terryman, to strike a crucial, finishing blow.

Comic Books

The comic book series Runaways does this with the Skrull Xavin a couple of times when we're getting to know him/her, although it's a case of short-circuiting (probably the Skrull equivalent of going into shock or throwing up from pain or whatnot), not actual death.

Film

Terminator 2, when the T-1000 fell into the molten iron.
In the X-Men movie, when Mystique was stabbed, even though she survived.
- Even worse in the second one, when Cerebro-2 almost kills her (and every other mutant on earth). She survives again, of course.
Randall, The Dragon from Monsters, Inc.., goes through several camouflage forms when Boo strangles him (but no, he doesn't die, because it's a Pixar film).
- This also happens to Mater in Cars 2 when he accidentally smashes the light used to disguise himself while infiltrating the Lemon meeting.
An interesting non-magical example occurs in Tropic Thunder with the dedicated method actor Kirk Lazarus briefly playing previous roles before reverting to his original identity.

Literature

Discworld example: the monster in Moving Pictures has just been a giant woman carrying a screaming ape to the top of the tallest building in the city (what's wrong with this picture?). When it falls, it changes into several different things on the way down, trying to find a form that can survive the fall. Unfortunately, as the narration notes, the only thing that could make that kind of fall is a corpse.
Ols from Emily Rodda's Deltora Quest series do this as they die.
Stephen King's It culminates in a psychic battle between Bill and Pennywise based on an ancient ritual of dominance. The monster cycles wildly through all his horrifying faces in a futile attempt to escape.
Dean Koontz' Shadowfires features this—at the end, the regenerating, mutating villain shifts through a variety of forms as his metabolism burns out. His accelerated metabolism consumes him, leaving a pile of goo. (Koontz likes to do this to regenerating characters.)
A story in The Martian Chronicles, by Ray Bradbury, may be the Trope Maker, if not the Ur Example: The title character of "The Martian" appears to whoever sees him as a lost loved one. When he's surrounded by a crowd of people, who all need to see somebody different, the results are not pleasant.
In The Silmarillion, Sauron is caught in a headlock by the hound Huan, and flips through several forms in an attempt to escape. He fails, and only escapes by shedding his body.

Live-Action TV

The Twilight Zone episode "The Four Of Us Are Dying," a man who can alter his face to look like someone else's goes through a convulsive process of his face taking on the shape of each one he impersonated as he lies dying from a gunshot.
A few variants in Heroes:
- When Sylar kills an illusionist, we cut away from the scene, and by the time we get back all we see is her lying in a pool of blood in her real (and fat due to all the junk food...) form.
- When a real shapeshifter shows up, it still doesn't happen, handily enough for Sylar, whose form he'd taken before dying.
- In a season finale, Peter uses his own copied shapeshifting power to overload Sylar's, causing him to shift through all the forms he had taken. This distracts Sylar long enough for Peter to jam an elephant tranquilizer syringe into his throat. Also a Crowning Moment of Awesome.
At the end of Roswell's first season, the protagonists used alien technology to heal a shape-shifting associate, who promptly exhibited this trope.
Inverted in Buffy the Vampire Slayer: the First Evil's (re-)introduction as as a Big Bad starts with a shapeshifting rundown of past archvillains. In the finale, the First slinks away unseen when its plan starts to go bad, and is never heard from again.
In the Mystery Science Theater 3000 episode The Undead, the evil shapeshifting witch comes to the sattelite to threaten Mike and the bots. Unfortunately, she seems to be suffering from some severe indigestion, resulting in this trope. She gets stuck in the form of a bottle of bleach.
One of the Dopants from Kamen Rider Double goes through these before entering its true form. These include a preist, another dopant, a pop idol singer, Shotaro's deceased mentor, and Kamen Rider Skull, who is also the deceased mentor.

Oral Tradition, Folklore, Myths and Legends

The Scottish ballad Tam Lin, where Janet, pregnant with Tam Lin's child, must drag him from the procession of fairies taking him to his doom, and hold on to him as he shapeshifts, until he turned into a burning coal, at which point he could be dropped into a well to return him to human. It makes more sense in poetry.

Tabletop Games

A recurring villain in a series of published Eberron adventures has something akin to this happening to him near the end of the last module; Grasp of the Emerald Claw. Garrow, a changeling cleric who has been dogging the party to retrieve the Macguffin starts to lose control to said Macguffin (which is now sentient), causing him to shift through the various guises he's used to fool the party: a vampire, a half-elf airship captain, a dumpy-looking woman and a few others that he would've used before ever learning of the party. This happens at the start of his last meeting with the party (at least in published material).
In the Ravenloft setting, the doppelganger darklord Sodo is cursed to be in a permanent state of this trope.

Video Games

In the original Mortal Kombat, defeating the final boss Shang Tsung—who has the ability to become any other character and use his or her moves—results in his effectively shedding all the characters' forms before he dies. It's less a song than a curtain call though, as each character separates from his body (with name announced) and combusts. This also happens to Shao Kahn in MK3 and its updates, except Kahn isn't a shapeshifter like Tsung.
- He plays it straight in the opening to Shaolin Monks though. Every time Liu Kang hits him near the end of the fight, he transforms into another character, looking disoriented the whole time, as though it's a survival reflex as described on the top of the page.
Happens to a shapeshifting hench in the Tex Murphy game Under A Killing Moon, except the guy starts out in his own form and ends up as a gooey blob.
In Metroid Fusion, the SA-X starts to do this... but doesn't quite finish, becoming a One-Winged Angel Biological Mashup instead.
- In Metroid Prime 3, Gandrayda shifts through the forms of various other bosses as well as copying Samus herself as you fight her, and her Shapeshifter Swan Song rapidly cycles through the various other boss forms before lingering on Samus's own form as it is (Suit upgrades and all) for a good long moment. This leads to a particularly striking moment with the real Samus, by this point badly corrupted by glowy blue Phazon energy, standing victorious over the image of her own uncorrupted self in the midst of her death throes. Samus is pretty much affected by this nightmarish death, she looks away and does nothing to stop Dark Samus from absorbing Gandrayda
When the shapeshifting boss Shadow is defeated in Castlevania: Harmony of Dissonance, it shifts rapidly through its three forms before burning away.
Defeating Wilfre in Drawn to Life: The Next Chapter will cause this to happen to him.

Western Animation

The introductory episode for Clayface in Batman: The Animated Series, "Feat of Clay", had Bats trick him into entering a room filled with TVs showing all the roles he'd played over the years (he'd been an actor). He started convulsing and turning into them at random (see the quote above); as he smashed the TVs, he was electrocuted. However, at the end it turns out the whole thing was an act, or at least the dying part, and Clayface survived, making this a subversion.
Happened to Chameleon in the Spider-Man: The Animated Series. In this case, it was his belt malfunctioning after Spider-Man attacked him, as he needed the technology to shapeshift.
Happened in Futurama to a shapeshifter who used his powers to juggle several different women in simultaneous relationships. Being confronted by all of them at once leads to him rapidly changing his appearance to appeal to each one (and to them beating the crap out of him so bad he starts to mix up aspects of the different forms before giving up and showing his true form).
Happens to Bowser in the Animated Series based on Super Mario Brothers 3, after Iggy and Lemmy/Hip and Hop build him an amulet that endows real-world mushrooms, flowers, etc. with the powers of those from the game. He goes a little crazy, mixing and matching Powerups (a fiery orange Bowser in a Kuribo shoe...and raccoon tail), and when he's defeated, the amulet malfunctions, causing him to blink through several different forms (raccoon, frog suit, orange (fire powerups on the NES made you a lot more orange!)) and odd mixings before finally rocketing him into a manhole.
X-Men: Evolution: Sort of happens to Rogue near the end of "Self-Possessed" during her superpower meltdown, but she does survive.
In an episode of Darkwing Duck, the villain, who was a Chameleon, went through one of these when she was exposed to warm temperatures and her metabolism speed up, resulting in her turning into an actually chameleon
Minor superhero Chameleon of The Tick (animation) suffers a mild form of this when he accidentally tries to conceal himself on some plaid curtains.
Happens to Static Shock villain Omnifarious when he uses the gas that gave various people superpowers (including Virgil) to try to destroy his father's company HQ. The dose turned out to be too heavy and caused him to mutate like mad and turn into stone.
The Terminator 2 example above was spoofed in a Halloween Special of The Simpsons, where Groundskeeper Willie as Freddy Krueger turned into many things at once, after having been trapped in quicksand and desperately trying to get out.
Minor example: In the ReBoot episode Painted Windows, Bob uses Paint of all things to remove Hexadecimal's mask. He then gets a Hannibal Lecture from all of Hexadecimal's faces as she starts to overload.