No Immortal Inertia

An extension of No Ontological Inertia and This Was His True Form. When an immortal and eternally youthful character has his (or her) immortality taken away, his years have a tendency to catch up with him, with tragic and often grisly results.

Bonus points if they (rather spectacularly) crumble away into dust, and further bonus points if said decay starts with the skin and moves inward, saving the character's skull for last.

In other words: What happens when a magically Really Seven Hundred Years Old character is forced to look her age.

Also, usually this depends on the particular immortal's place on the sliding scale of morality. A really, really nice immortal? Probably was trying to get rid of his immortality and live a normal human life anyway, and most of the time starts aging at a normal pace instead of crumbling into old age. A selfish immortal, or an immortal villain, or someone whose immortality was Powered By a Forsaken Child? Much higher chance of this happening. Even more likely to happen if Liquid Assets were exploited to cause the youth to begin with. Shape Shifter Swan Song is similar but for shape shifters.

Related to Age Without Youth.

Anime & Manga

 * The Cowboy Bebop episode "Sympathy for the Devil" had an immortal child named Wen whose circadian rhythms were disrupted due to the gate explosion that makes up part of the series Backstory, resulting in him not aging like he should..
 * In the film of Howls Moving Castle: The Witch of the Waste manages to survive her Immortality Failure, only to age, shrink, and become slightly senile.
 * In Witch Hunter Robin, a Witch of the Week who had been alive for apparently thousands of years by feasting on others' life force crumbled into mere sand when his powers were taken from him.
 * Tsubaki from Inuyasha had this happen when all of her yōkai were killed and her jewel shard was taken back by Naraku. In the manga, she just began to look her true age (about the same age as Kikyo if Kikyo hadn't died); in the anime, she turned into dust.
 * Averted (and, to an extent, inverted) in Code Geass. When V.V. loses his Code, he just dies, though that's almost certainly from the injuries sustained in a Humongous Mecha battle earlier that episode. When C.C.'s Code is temporarily sealed, she mentally regresses to the last point in her life where she was mortal - which was when she was 10 years old and living in the Dark Ages. Dialog in a later episode implies that this has happened to her before.
 * Used to an extreme in XXX Holic due to the details of the prolonged existence of the immortal in question. When said immortal dies several hundred years after they were meant to, not only does their body vanish (presumably into the scattered dust it would otherwise be by now), but almost everyone's memories of  vanish and adjust to how they would be if   had died on schedule.
 * in Fullmetal Alchemist shows the marks from transmutation all over his skin when he loses all the philosopher's stones in his body. Then he ages to what is not exactly his true age, but old age nonetheless and dies by the end of the day... ish. Traveling to probably took a little while.
 * Similarly, once  Philosopher's stone runs out, he ages rapidly.
 * Tsunade of Naruto has something that looks a bit like this. She's in her 50s (at least) but wears an illusion to make her appear much younger. She also focuses most of her chakra on the seal on her forehead as a reserve which she can draw on in battle to give her perfect regeneration - at the cost of increased aging. At the end of the battle she is too tired to be able to maintain her illusion, which looks like massive rapid aging - but there's no way to tell just how bad the extra aging she took was, since we don't know how old she really looked under the illusion beforehand.

Comic Books

 * Happened to Captain America after he died. In one alternate future in Ultimate Marvel, he died instantly due to this when his Super Serum was nullified.
 * In Fallen Angel, Juris, sick of being Magistrate of the magical Genius Loci city Bete Noir, passed the mantle onto his son so he could finally leave the city. Upon going beyond the city limits, he aged rapidly and ultimately crumbled to dust.
 * In Sonic the Hedgehog/Knuckles the Echidna, mad scientist Dimitri, after messing with a Chaos Emerald, wound up absorbing its power, and was trapped under a mountain for hundreds of years. Knuckles accidentally 'woke' him up, and Dimitri, now calling himself Enerjak, set about to conquering Knuckles' home land. However, when Mammoth Mogul came to the scene, he used the Sword of Acorns to drain all of the Chaos energy from Enerjak, and all those years definitely caught up to him. He was forced to live in an entirely robotic body just to survive, and many issues after that, only his robotic head is alive. (If you can call that 'living'.)
 * Selene tends to age very rapidly when her store of life force runs low.
 * Happens a couple of times in Thorgal, always milked for all the Nightmare Fuel it is worth.
 * To explain how Nick Fury remains relatively young while being a World War II vet, it was revealed that he was dosed with an experimental "Infinity Formula" by a doctor who found the wounded Fury after he stepped on a land mine. For a while, if he stopped taking it, he'd age rapidly - not even up to his current age, but past it. After a few decades, however, his body seems to have synthesized the stuff, and he no longer has the dependency.
 * The 1945 Marvel Family #1 (the first team-up of all the Marvels) featured the origin story of Black Adam. He originally gained his powers from the wizard Shazam 5,000 years ago. After he gained his superpowers he decided to conquer the world and Shazam sent him into outer space 5,000 light years away. Black Adam spent the next 5,000 years traveling back to Earth at the speed of light, arriving in modern times. The Marvels tricked him into saying the word "Shazam", which changed him back into his non-powered form. Unfortunately for him his accumulated age caught up to him and he suffered from Rapid Aging, turning into a skeleton.

Fan Fiction

 * In the Final Fantasy VII fanfic Does Fate Allow a Second Chance?, is older than he looks and is on a quest to become mortal.

Film

 * The League of Extraordinary Gentlemen film: The same Dorian Gray after he sees his portrait. Justified by the mechanism of his immortality: the aforesaid portrait took the effects of aging and injury for him.
 * The grisly fate of Morgan Le Fay in Excalibur, rendered in a very Nightmare Fuel-Efficient way.
 * In Forever Young, Mel Gibson's character was cryrogenically frozen for almost 50 years, and didn't age during that time. However, the effect wore off and he eventually aged, looking the same as he would have if he hadn't been frozen. (Which worked out well for him, since he could then be reunited with his lost love, who was now an old woman.)
 * In Bullet Proof Monk, at the end of each monk's tenure, when he passes the power of the scroll on to the next monk after fifty years of agelessness (and bulletproofness), he reverts to his natural age.
 * In The Lord of the Rings: The Fellowship of the Ring, Bilbo Baggins looks as young as he did when he first met Gandalf when he still possesses the One Ring. After leaving it behind for Frodo and traveling to Rivendell, his Ring-deferred years catch up with him and Bilbo becomes quite elderly. (In the book, there are 18 years between Bilbo's departure and our catching up to him at Rivendell; in the film it seems to be a few months.)
 * Played straight in the Ishiro Honda movie Latitude Zero at the death of.
 * The Hunger has a true vampire who can only provide her playthings with youth for about two hundred years; after that, time rapidly catches up with them, and they become dessicated husks. She usually keeps these husks, for sentimental reasons.
 * The film adaptation of She, when the title character makes the mistake of re-entering the fountain of youth.
 * In Tangled, Rapunzel's hair can heal and restore youth, but if said piece of hair is cut, the person who gained youth from it, begins to age rapidly.
 * This may also be because said person was clutching the hair as it lost its power.
 * There is a German gay porn movie named Boytropolis, which depicts a community of guys living in the jungle, minding their own business, and keeping themselves young and handsome by drinking a potion made out of plants. If they're deprived of it, they melt.
 * Horror of Dracula has a hot young vampiress who turns into an old corpse when staked.
 * Zordon starts aging "at an accelerated rate" when Ivan Ooze breaks him out of his time-warp capsule in Mighty Morphin Power Rangers. Later in the film, the immortal Dulcea tells the Rangers that she too will rapidly age if she leaves her domain on the planet Phaedos.

Game Books

 * Book 17 of the Lone Wolf series The Deathlord of Ixia combines this with Load Bearing Boss. Killing the titular Big Bad breaks the enchantment that kept the city of Xaagon in a suspended state. The moment Lone Wolf strikes the killing blow, milennia of wear and tear catch up to the city, and Lone Wolf has to haul ass out of there. Breaking the spell also removes the permanent cloud cover over the city, allowing sunlight to warm Ixia again.

Literature

 * In The Picture of Dorian Gray, Dorian is kept eternally young while his picture turns hideous and ancient. When he destroys the picture, his servants find the picture of a young Dorian and a crumpled, ancient corpse on the floor, only recognizing him by his ring.
 * "The Facts in the Case of M. Valdemar" by Edgar Allan Poe.
 * In Much Fall of Blood, this happens to . Somewhat justified in that the immortality treatment had to be maintained at regular intervals.
 * The Dresden Files:
 * Cassius is a Denarian who surrenders his immortalizing Phlebotinum coin so the honorable Knights won't kill him. He taunts the knights by saying he need only return to the Big Bad for a replacement coin, but he never manages it. The next time Harry sees him, Cassius is an incredibly old and desperate man.
 * In "Changes," the
 * In Perry Rhodan, the devices providing certain main characters with immortality, poison resistance, and improved natural healing were for the longest time simple pendants usually worn on a chain; if ever lost or destroyed, the wearer had about 62 hours to live before dying of accelerated cell decay. (After a couple of millenia or so of use and a crisis involving their creator, these have been replaced by implanted chips.)
 * In one of the later Oz books (by Ruth Plumly Thompson, not Baum, but still canonical), Dorothy returns to the United States, and starts getting older. Luckily, it's reversed when she goes back to Oz.
 * H Rider Haggard's novel She. Thousands of years ago Ayesha stepped into a pillar of fire and became immortal. At the climax she steps into it again and reverts to her true age, withering and dying.
 * In one early-ish Xanth book, Electra begins aging rapidly when she enters the magic-less Mundania. Incidentally, she's not actually immortal, she just slept for 700 years.
 * Bilbo Baggins in The Lord of the Rings begins to age at a somewhat accelerated pace after giving up the Ring, although he still lives for at least 20 years afterward. (In the movie, where the intervening years between Bilbo's farewell party and Frodo leaving Hobbiton are seemingly compressed to a few weeks or months, it's far more apparent.) Interestingly, Gollum, who had the Ring a lot longer than Bilbo, is still alive and mostly unchanged 75 years after losing it, probably because he was also a lot more corrupted by the Ring than Bilbo was.
 * Gollum comments, however, that if the Ring is destroyed, he will "die into the dust," which fits this trope exactly, aside from him not getting the chance.
 * It was implied that this would also happen to the 3,000 year old Nazguls upon the Ring's destruction, but this wasn't explicitly shown. In an indirect sort of way, this happened to the bearers of the elven Rings as well: the bearers are all immortal without the Rings, so we don't see them becoming older, but what happens to Elves as they age is that they tend to leave Middle-earth for Valinor...which is exactly what Elrond and Galadriel do a year later.
 * Played with in Stationery Voyagers: Final Hope. Laura herself becomes a little stronger and a little more Badass every time she dies, until she's practically Made of Iron. But her budding romance leads her to crave companionship and the one thing that can defeat her. When she does lose her virginity, the Crimson Owl abandons her instantly. Her muscle mass and muscle memory disappear within minutes until she is as unskilled a fighter when she gets out of bed as she was before she died the first time. The rest of her doesn't age or show ill effects, but she becomes so distraught at her loss of skills that she fears she'll endanger the team if she stays aboard. So she attempts to quit; and is assassinated by Astrabolo's forces anyway. Very Genre Savvy, she is, about the Sorting Algorithm of Mortality.
 * The first book of the Mistborn series uses this trope. The Big Bad, who has essentially been the emperor of the entire world for the last thousand years or so managed to obtain immortality by heavily abusing multiple forms of magic, essentially keeping himself young with a number of magical trinkets. When they get removed, his youth does too.
 * The Secrets of the Immortal Nickolas Flamel series: not only are Nickolas and his wife rapidly aging without their book that has the recipe of the elixir of life (they can't rebrew it from the same process as last time because it changes every month and old recipes cause them to age faster). Also it is the standard punishment for an immortal that displeases their master Elder the have their immortality removed and quickly age to dust.
 * The alternate universe, somewhat more benevolent, version of Nicholas Flamel was used in the first Harry Potter novel. He had used the Philosopher's Stone for centuries as a part of the process of brewing an elixir of life, but after learning that Voldemort was seeking it out, he and his wife willingly turned it over to Dumbledore for safekeeping. The trope is played straight, though bent sideways; without the Stone, Flamel only has a limited supply of the elixir remaining. Just enough, Dumbledore says, to put his affairs in order and finish up last-minute business before he and his wife pass on. Though it's not explicitly stated, the tone of it is that he will eventually pass away quietly of natural causes, without any skin-sloughing ickyness. Fridge Logic tells us, however, that Voldemort's defeat several years down the line might've made him reconsider.
 * Discworld did a non-living form of this in The Colour of Magic. Time was too afraid of Bel-Shamharoth to go anywhere near its temple. After Bel-Shamharoth flees to the nether realms, the temple ages thousands of years in a matter of seconds.
 * Huh Time doesn't seem like she'd be afraid
 * I hear Dungeon Dimension Denizen blood is hell to wash out of your clothes.
 * The Meq subverts this by having the loss of their immortality be a vital part of their lifecycle.
 * Inverted in The Wheel of Time. The Aes Sedai have very long lives and an ageless appearance, but after losing their powers, they suddenly look much younger. Two characters who are really in their forties now look like twenty-year-olds.
 * In The Spiderwick Chronicles, people whose lifespans have been prolonged by elven magic will age and die as soon as their feet touch the ground.
 * Oskar Matzerath from The Tin Drum was a three-year old adult who remained a child out of his own free will. Once he had enough, he underwent the same process to reverse it. His years caught up to him immediately, although he was in his twenties at the time so it wasn't as dramatic as other examples here.

Live Action TV

 * Heroes has Adam Monroe, when he got his ability stolen by Arthur Petrelli.
 * They try to explain it by the fact that, over the centuries, Adam has died and was damaged so many times, that his Healing Factor kicked into overdrive. His cells are continuously dying and recreating. So, when you remove the "recreating" part, it's clear why he suddenly crumpled into dust. It's possible that Claire will have the same problem in a few hundred years.
 * Space 1999 episode "The Exiles": A man had his youth preserved by a skintight membrane covering his body. When it's ripped, he rapidly ages.
 * Also done in the episode "Death's Other Dominion": something about a certain ice world kept the survivors of an exploratory ship unaging for centuries. When one of them tries to leave....
 * The Twilight Zone TOS episode "Long Live Walter Jameson": A man lives thousands of years due to a potion of immortality. When he's shot, the effect wears off and he ages into dust in minutes.
 * The Outer Limits:
 * TOS episode "The Guests": Several people are trapped in a house where Time Stands Still. If they leave, they grow old rapidly and die.
 * Something like this happens in one of the new series episodes: a scientist finds a way to seemingly keep people young and immortal, however it is discovered that this is done by hyperstimulating the cells of the person in question, thus causing them to eventually grow old and die in a matter of weeks.
 * The pilot episode of Eerie Indiana had a woman who was keeping herself and her children young forever by sealing them in bed-sized tupperware containers every night. When she was stopped, the three of them aged 30 years overnight.
 * In the first season finale of the Sci Fi series Sanctuary, James Watson (almost THAT John Watson) finally dies. He had lived for over one hundred years thanks to a combination of Applied Phlebotinum and a special mechanical device that kept him young, but the device finally failed and Watson died from accelerated aging.
 * A flashback episode shows Watson being tortured by John Druitt by turning the device on and off, causing Watson great pain.
 * The Master does this to the Doctor in Doctor Who by suspending his capacity to regenerate with a laser screwdriver.
 * Also in "State of Decay" - when the Great Vampire is destroyed, The Three Who Rule's thousand years of unlife suddenly catches up with them...
 * Star Trek the Original Series episode "Miri." Children live for hundreds of years due to a virus, but when they reach adulthood they quickly grow old and die.
 * Hex has immortal witch Ella Dee. At one point, Azazeal foils Ella by cutting off her powers with St John's Wort. This has the effect of rendering her mortal, and, well, how many mortals do you know that are over the age of 500?
 * In The Hugga Bunch special, the evil queen Admira stays young by eating the fruit of the Youngberry tree at regular intervals. When the protagonists prevent her from getting the berries in time, she suddenly becomes wrinkled and eventually falls still, her skin turning ashen.
 * Possibly averted in the fifth season of Angel. When Jayne shows up to replace Eve, she loses her immortality. Of course, we don't know how old she was.
 * Averted in Lost -
 * In the Are You Afraid of the Dark episode "The Tale of Many Faces", the Big Bad falls dead and turns into a skeleton when given back her original face.

Myth And Legend

 * In (some) folklore, usually what happens to vampires if you manage to actually kill them.
 * In the Japanese folktale of Urashima Tarou, the title character returns home after living it up in the undersea kingdom, having been given a box to never open. Turns out a long time has passed on land and everyone he knew is now dead because there's no aging in the undersea kingdom. He decides he has nothing left to lose and opens the box, causing all of his age to catch up with him.
 * This is also a recurring theme in the Western fairytales where the protagonist is spirited away into the Fairyland for centuries without realizing or feeling the passage of time. Sometimes they would return to the human world, only to discover that in the meantime year, decades, or even centuries had passed while they hadn't aged. Upon their return, all that missed time would catch up with the victim spectacularly.
 * In one fairy tale, a human newly returned from fairlyand has to actually touch the ground for the aging to kick in, presumably because otherwise he hasn't really returned to the mortal world yet. His fairy wife/girlfriend/whatever lets him return on a horse, warning him not to dismount; inevitably something makes him fall off, of course.
 * The Irish tale of [[http://en.wikipedia.org/wiki/Ois
 * This is why King Herla of The Wild Hunt can't get off his horse. He spent a few centuries at a fairy wedding party. As soon as he gets off of his horse (given to him by the fairies) and sets foot back on the earth of the mortal world, time will catch up and he'll age to death in a matter of seconds.

Tabletop RPG

 * Vampire: The Requiem:
 * The game makes it clear that the younger the vampire, the more... meaty the remains. Elder vampires just turn to dust when they die.
 * Additionally, Ghouls (humans fed on vampire blood and granted some of its power) do not age as long as they get a dose of vitae once a month. If they miss it however, they rapidly age-up until they're where they should be.
 * The same is true of both vampires and ghouls in the earlier game Vampire: The Masquerade.
 * While the spell "Polymorph any object" in Dungeons and Dragons could conceivably be used for immortality cheese, it is vulnerable to being dispelled, leaving them at either the age they started the cheese, or their actual age, depending on the DM.
 * One of the plots for a All Flesh Must Be Eaten campaign has an evil Chinese alchemist who found the formula for immortality. Some of the rare herbs just went extinct and he's looking for replacements, but he has to hurry because he's aging a year each month.
 * Call of Cthulhu adventures
 * "The Secret of Castronegro". Bernardo Diaz has lived for 300 years due to the ruby ring he wears. If it's removed from his finger, he will instantly die and his body will shrivel.
 * The Fungi from Yuggoth. Lang Fu's Coat of Life has allowed him to live for centuries. If it is ever removed for more than a few minutes, his body will begin an irreversible aging process that will cause his rapid death.

Video Games

 * Briefly appears in Mother 3, afflicting the protective vines around Chupichupoyoi Temple.
 * As Okami takes place in a Fantasy Kitchen Sink of Japanese myths and legends, it's unsurprising that Urashima shows up.
 * Morrowind left inconclusive the effect of losing the immortality of Lorkhan's Heart. Dagoth disappeared in a pool of lava beneath a collapsed cavern, Sotha Sil was murdered, some decay was suggested in Almalexia's case but she dies in battle, and while Vivec could be killed by the player, according to canon he mysteriously disappeared.
 * It's been suggested, but not confirmed, that a weird or mild form of this is happening to the night elves in World of Warcraft. According to the lore, they are naturally long-lived on the order of a lifespan of a few hundred years, they were magically granted immortality ten thousand years ago, and it was revoked less than a decade ago. After less than a decade, some are starting to show signs of age beyond where they left off; for example, Tyrande Whisperwind (leader of the night elves) was a young adult at the time of being granted immortality. In the game right now, she's developed fairly noticeable crow's feet, even though if she were to continue aging normally from where she left off, that shouldn't happen for centuries. It's left vague whether this is age catching up to the elves or simply the effects of stress(which they are under a lot of), however.
 * Aegwynn is in a similar boat, using her powers as Guardian to extend her life for more than 800 years. After expending most of her magic  some thirty-odd years prior to Vanilla Wo W, she no longer has the power to keep herself young, and has been steadily aging as a result. Though the comics would show otherwise...
 * This is because, after her banishment, she comes back to use her remaining magic to resurrect her son (after he is decapitated by his own apprentice), who, in turn, used his powers to give his mother proper retirement. She is given a hidden house in a valley in Kalimdor, protected by multiple wards (one of which keeps her healthy) and thunder lizards. Then Jaina Proudmoore decides to settle the valley...

Western Animation

 * One episode of Justice League Unlimited ended with Morgan Le Fay's spoiled son keeping his immortality, but losing his youth, turning him into a shriveled, toothless and senile old man.
 * A Totally Spies episode features an age-sucking villain. When the heroines disable his magic crystal thingy, he crumbles into dust.
 * A Freakazoid! episode has the villainess dying in such a manner when she fails to drain Freakazoid's essence in time.
 * The zombies and cat monsters in Scooby Doo On Zombie Island.
 * In a Nightmare Fuel moment for the Captain Marvel cartoon, the villain Black Adam was tricked into saying "Shazam," and reverted to his "mortal form." He hadn't previously assumed that form in several thousand years, being a native of ancient Egypt. He crumbled instantly into dust. An unexpected Family Unfriendly Death, made worse by the normally Technical Pacifist heroes manipulating him into killing himself.
 * This actually happened in the comic book too.
 * And there's a similar sequence in Batman the Brave And The Bold.
 * Also happened in the direct-to-dvd crossover with Superman, only it wasn't Captain Marvel who made Black Adam transform back.
 * In Adventures of Sonic the Hedgehog, Robotnikotep IV actually disintegrates after having the Chaos Emerald of Immortality taken from him by his descendant--however, he seems vaguely happy about this because it frees him from having to deal with a mummified blue hedgehog.
 * In the Samurai Jack episode "Jack and the Lava Monster," Jack defeats a warrior who had been immortal for thousands of years as a punishment from Aku. He immediately ages to look about 80, but that's still pretty spry for someone in their thousands.
 * Averted in Highlander the Animated Series, where most of the immortals had performed some kind of magic ritual that allowed them to transfer their special skills to The Chosen One without doing the whole head-cutting-off-thing. Instead of dying upon transfer, they simply lost their immortality and would live out a natural lifespan from whatever their physical age was. Considering they lived in a post-apocalyptic wasteland, though, this probably wouldn't take very long.
 * Especially since, oftentimes, the heroes were one step ahead of Kortan's forces. A few times, the Jettators (former immortals) who had just given their knowledge and power to Quentin McLeod would be forced to face Kortan himself in combat. Not only are they too weak to defeat Kortan, but said magic ritual also means that any Jettator who breaks his oath (i.e. fights another immortal) is destined to die.
 * Their swords being shattered by the ritual probably didn't help either.