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[[quoteright:350:[[Webcomic/{{Nedroid}} http://static.tvtropes.org/pmwiki/pub/images/iusedtolooklikethis_6180.jpg]]]]
[[caption-width-right:350:"[[WesternAnimation/GIJoeTheMovie I wasss once a maaaan! Once a maaaaan!]]"]]

->''"I'm an insect who dreamt he was a man and loved it. But now the dream is over... and the insect is awake."''
-->-- '''Seth Brundle''', ''Film/TheFly1986''

[[OurMonstersAreDifferent Monsters]] are pretty damn scary. Horrible, bug-eyed, slobbering, and in ''no way'' '''''ever''''' human. Therefore, it's all the more [[NightmareFuel unsettling]] when it's revealed that a monstrous creature (almost never the main character) was once human, but became a monster through some sort of [[TheVirus infection]], [[TheCorruption curse]], sheer [[EvilMakesYouMonstrous personal evil]] or [[TransformationTrauma transformation]]. And there's no means of changing them back.

Related to BodyHorror and FaceMonsterTurn, but distinct in that while BodyHorror deals with the fact of the monstrosity itself and usually follows it from beginning to end, Was Once a Man is where a creature is monstrous when first introduced, but is either implied heavily or later revealed to have once been human.

Sometimes the mind is not affected; [[ViralTransformation only the body is]]. And sometimes [[IKnowYoureInThereSomewhereFight the original mind can be reached.]] This does not undermine the horror of it. Indeed, in certain ways, it [[TragicMonster makes the horror even]] ''[[AndIMustScream worse]]''.

See also: BodyHorror, ViralTransformation, TheVirus, TragicMonster and StagesOfMonsterGrief. Compare ''and'' contrast UncannyValley. Also contrast with AscendToAHigherPlaneOfExistence, for a non-monstrous transformation.

This trope has nothing to do with GenderBender. Also not to be confused with [[BawdySong Was Once A Man From Nantucket]].

----
!!Examples:

[[foldercontrol]]

[[folder:Anime and Manga]]
* The manga of ''ChronoCrusade'' has an unusual example revealed towards the end: [[spoiler:[[HiveQueen Pandaemonium]] was once a human woman pregnant with twins. The demons kidnapped her and transformed her into the monstrous, MindRape-using queen she is -- and transformed her human children, Chrono and Aion, into demons as well.]]
* In ''XamdLostMemories'', it becomes clear fairly early on that both humanform weapons and Hiruko are former humans.
* Each and every of the Awakened Beings in ''{{Claymore}}''. And, perhaps more shockingly, the Abyss Eaters. Even more shockingly, [[spoiler:the Youma.]]
* Every demon in the ''{{Berserk}}'' universe was once a human. Humans become demons when a creepy little egg-like item called a Behelit comes into their possession and they hit an [[DespairEventHorizon emotional nadir]] where they will do anything to get out of their current situation. At this point, the Behelit rearranges the features scattered upon its surface into a human face and screams, which summons the demonic gods of the Godhand, who proceed to [[DealWithTheDevil offer him the chance to become a demon in exchange for the sacrifice of those closest to them]]. It also turns out that [[spoiler: every member of the Godhand was also human, and they are created with the use of Behelits as well]]. While demons do sometimes retain the personalities they had when they were human, all too often they commit TranshumanTreachery, with many of them preferring to [[ImAHumanitarian dine on their former species]]. When demons die, they typically [[ThisWasHisTrueForm revert to their former human forms]] after their spirits are DraggedOffToHell.
* Anna from ''Manga/ElfenLied''... Dear ''God'', Anna. [[spoiler:When first introduced, she is an adorable and happy, if dimwitted, young girl who loves to run. Her father is disappointed with her lack of intelligence, and transforms her into an enormous, horribly mutated creature with super-intelligence and precognitive ability. She cannot support the weight of her gigantic head, and so must remain virtually immobile in a pool. Remember how she loved to run? [[BlessedWithSuck Yeah.]]]]
** [[spoiler:She gets better, and in perhaps the CrowningMomentOfHeartwarming of a very dark story, she is overjoyed when she realizes she can't do simple math.]]
* ''Manga/KingOfThorn'' has the "mother monster", which is eventually revealed to have been a human ([[spoiler:Shizuku]]) who succumbed to TheVirus.
* ''WorldEmbryo'' - The enemy virus, Kanshu, were once humans who lost their memories and transformed into hideous beings upon listening to the infected radio signals in their cell phones.
* ''Manga/{{Bleach}}''. Every Hollow started out as a lost human soul. Eventually, it lost its heart, whether through time or the attacks of another hollow, and became a monster, feeling nothing but the desire to murder and a hunger for souls.
** If they survive long enough, Hollows can "get over it" on their own (or if someone else removes their mask or uses the Hogyoku on them) and become Arrancar, who are intelligent creatures and apparently don't need to eat souls anymore (considering that they have copious amounts of regular food in Las Noches and only three or so Arrancar are ever shown any desire to eat anyone... and of those, one is a MadScientist who's turned his minions into edible medicine and another has the ability to gain the powers of anyone he eats, so they're not just eating for the sake of eating.)
* Similarly, the Akuma of ''Manga/DGrayMan''. As with Hollows, their hunters know, at least in abstract that they contain the souls of innocent people forever tortured until the Akuma are destroyed and they're released, but only Allen has to confront the vision of them on a daily basis. As with Hollows (though in Bleach it's a different story), leveling up obscures more and more the original souls, until even Allen can't see them anymore. It also makes new souls in the process.
* Some of the monsters in ''Anime/SailorMoon'', were (for the most part) originally human. Some of the Youma in the first season and the Phage of the last season. Sailor Moon's power to restore the Phage to normal actually shocks the Starlights, as they had to simply destroy them because they lacked the ability to do so. (Though they implied their Princess could, as they stated they had to destroy them without her around). A single human-based Daimon also appeared in a flashback which was closer to their [[Manga/SailorMoon manga]] version.
* Hakkai from ''Manga/{{Saiyuki}}''.
** Though he's not terribly monstrous or ''in''human now, even in his demon form, and only really has to avoid it because ''the minus wave currently makes demons AxCrazy''.
* In ''Anime/PuellaMagiMadokaMagica'', it turns out that [[spoiler:every single one of the Witches that the magical girls fight (those that aren't ex-familiars, anyway) was once a magical girl herself]], and to make things even worse, [[spoiler:every magical girl is ultimately doomed to [[AndThenJohnWasAZombie become one of the very monsters she's been fighting]], unless she dies first.]]
* In ''Manga/FullmetalAlchemist'', [[spoiler:Shou Tucker, the Sewing Life alchemist, fuses his adorable daughter Nina with her dog, Alexander. He also fused his wife with another beast a few years back, in order to gain his certification. Both chimeras are able to talk, and they both made it known they were ''not'' happy with their new existence. The one made of his wife asked to be killed and when it wasn't obliged it starved itself. The one made of Nina and Alexander is killed by Scar.]]
* The dragon [[spoiler:Acnologia]] from ''Manga/FairyTail'' was originally a slayer. After killing countless dragons he was apparently a turned into one himself by Zeref.
* ''Franchise/YuGiOh'':
** Yubel, the BigBad of season three of ''Anime/YuGiOhGX''. She [[spoiler: willingly gave up her humanity and was turned into a demon in order to become a spiritual guardian for her ward (who would become Judai in a later life).]]
** All of the villains originating from the BadFuture of ''Anime/YuGiOh5Ds'', including Z-one, Aporia, and Paradox. The first is a cyborg with god-like powers, while the other two are android incarnations of their previous selves.
** The Seven Barian Emperors, the antagonists of the second season of ''Anime/YuGiOhZexal'', were all once human, and they can assume human forms that resemble - for the most part - their original forms.
* ''Manga/OnePiece'' has the island of [[spoiler:Dressrosa. There humans and living toys live together. Except unlike other fantastic beings in One Piece, these "toys" were once humans but turned into toy creatures]] by a Devil Fruit user.
* In ''Manga/AttackOnTitan'', [[spoiler: Titans were once human. The only difference between Shifters like Eren and regular Titans is that he was able to control the power. Regular Titans appear to have fully absorbed their human "pilot", reducing them to mindless horrors that seek out humans to eat. Ymir was able to regain her humanity after 60 years, though the exact method is unknown. It is, however, hinted to involve the fact that she ate a suspected Shifter around the same time....]]
* In ''Manga/AhiruNoOujisama'', Mister was once a prince, but is now an ugly dog. [[spoiler: He turns back...after being a short ugly weirdo for a bit he gets back to being a bishonen.]]
* In ''Manga/{{Naruto}}'' the [[spoiler:thousands of Zetsu clones]] were victims of the first [[LotusEaterMachine Infinite Tsukiyomi]] rather than [[spoiler:clones of Hashirama]]. The end goal of [[spoiler:Kaguya]] is to create an army using the same technique.
** The Juubi was created when [[spoiler:Kaguya merged herself into the God-Tree]].
* In ''Manga/MagiLabyrinthOfMagic'', all the Djinns were revealed to be once members of the sentient species that were freed and later allied with Solomon.
* This happens a ''lot'' to people who go under FrankenFran's scalpel, or that of her creator.
[[/folder]]

[[folder:Comic Books]]
* ''ComicBook/JudgeDredd'':
** [[RealityWarper The Mutant]], a hideous multi-limbed...thing from an alternate future timeline where he tortured and killed Judge Dredd and Judge Anderson, as well as destroyed Mega City One, ruling over the ruins along with the now corrupted and mutated judges. [[spoiler: He is actually Owen Crysler from The Judge Child storyline]]
** Another comic revolves around a man who is secretly given a serum based on dinosaur DNA by his upstairs neighbor, a MadScientist who slips it into his food. He ends up slowly devolving into a hideous reptile man, and eats and kills his wife and the scientist before Dredd is forced to kill him.
** Judge Death started out as human before he met the Sisters of Death, who transformed him into the undead monster we know him as now. When his fellow Dark Judges see the results, they ask for the same to be done to them. The Sisters themselves used their magic to cast off their mortal bodies as they entered the astral plane, then return to the world of the living as banshee-like ghosts.
** There's a rare genetic mutation which will slowly turn the afflicted person into a human-sized spider. PlayedForDrama in one comic when a woman with the condition is abandoned by her husband, PlayedForLaughs in another one when the test results of two patients are accidentally mixed.
* Invoked in ''ComicBook/StrikeforceMorituri'' with the "mutants", four humans who were accidentally turned into super-powered monstrosities when they underwent the Morituri Process without proper supervision.
* In ''ComicBook/{{Camelot 3000}}'', Morgan la Fay keeps an ape-like animal on a leash as a RightHandAttackDog. At one point, she informs an underling that it was once a man, until [[YouHaveFailedMe he got on her nerves]].
* ComicBook/{{Galactus}} of the MarvelUniverse was once a man of the previous universe named Galan. As his universe died to pave way for the new, current one, Galan journeyed into the center of the Big Bang refusing to give in to destruction. The powers that be were impressed and transformed him into Galactus.
* In ''{{BPRD}}'', it is revealed that [[spoiler: Abe Sapien]] was once a human named Langdon Everett Caul, and has been alive since the 19th century.
** Of course, there are several other examples in both ''BPRD'' and ''ComicBook/{{Hellboy}}'', such as the frog monsters, or the TooDumbToLive wannabe satanist aristocrat couple who fell afoul of minor demon Ualac in ''Box Full of Evil''.
* Played with in ''PaperinikNewAdventures'': the surviving Xerbians initially consider Xadhoom an alien monster (albeit an allied one), and are quite unsettled when they find out she was once their leader. Them expressing the wish to make her return to normality also caused them to receive a TheReasonYouSuckSpeech (with AGodAmI thrown in to hammer down she has no reason to return normal) before Xadhoom went for her [[spoiler: HeroicSacrifice]].
* ComicBook/SolomonGrundy was once Cyrus Gold, a merchant in 18th century Gotham City, who was murdered and whose body was dumped in the infamous Murder Swamps, where he rose once again as the unkillable Grundy, who would walk the Earth forevermore.
* Comicbook/ManThing was a scientist who, upon his death in a Florida swamp, was merged with an attempted recreation of the SuperSoldier serum that created Comicbook/CaptainAmerica that he had been working on, and became a hideous half man, half plant creature with only the most basic remnants of sentience left.
* Comicbook/SwampThing was once Alec Holland, who mutated into a swamp creature through similar means as Comicbook/ManThing above. [[spoiler: Or so he thought. Alec Holland died out there in the swamps, and the being that rose from the mud was a plant elemental with the absorbed memories and personality of Alec.]]
* Salem from ''ComicBook/SabrinaTheTeenageWitch'' was changed from a normal cat to, in the late 90s, into once having been a wizard who was punished to live 100 years as a cat because he tried to take over the world.
[[/folder]]

[[folder:Fanfics]]
* ''Fanfic/ImperfectMetamorphosis'': While never a man per se (on [[ImprobablyFemaleCast two]] [[{{Youkai}} counts]]), the BlobMonster (ie.[[spoiler: Rin Satsuki]]) definitely fits.
* In the ''Portal2'' fanfic ''Fanfic/BlueSky'' this is revealed to be [[spoiler: true of Wheatley, though he isn't pleased to realise it. He eventually makes it back to his real body.]]
** A lot of human!Wheatley fanfics invoke this.
* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' fanfiction ''FanFic/LegendsOfEquestria'' Discord reveals that he was once a unicorn in ancient times. However, he was transformed by the corrupting power of dark magic after accepting it in an attempt to restore order to his life after his family is killed.
** On a similar note, in [[AskAPony Ask Crapplejack]] it is explained in Equestria's prehistory that Discord was actually one in a race of Draconequusi, and were not twisted and ugly like him, but were beautiful and actually looked like dragons with horse features. Discord's transformation began when a war broke out between the Draconequus race and the race of Alicorns, who lived along side them, and he looked for a way to sway the tides, so he unleashed a powerful god of madness named Genuvial which corrupted his wisdom and body and loose sight of the war and decided to the world to chaos instead.
* The ''FanFic/PoniesOfOlympus'' series:
** Chrysalis and her subjects used to be normal ponies (implied to have been flutterponies, in fact), before [[GodOfEvil Erebos]] transformed them.
** And Discord used to be a pony named Endymion [[spoiler: and was Luna's lover]] before some unspecified event led to him trying to take [[PrimordialChaos Chaos']] powers and being consumed by it.
* Pretty much what a prolongued exposure to [[spoiler: gyroids]] do to people in ''TheTerribleSecretOfAnimalCrossing''
* In ''FanFic/PlasmasFolly'', Kelvin reveals that [[spoiler: Genesect is actually a middle-aged woman who had become terribly deformed as a result of Team Plasma's attempt to create a Pokémon with human intelligence. She was stuffed into a suit of robotic armor, which is the only thing holding her body together and keeping her alive.]]
* FanFic/TheNuptialverse has Chrysalis having once been a normal pegasus who made a [[DealWithTheDevil deal with Discord]] for power (she thought he was going to make her an alicorn; he [[JerkassGenie thought that was too boring]]). Likewise, the other changelings were once flutterponies until Discord needed to give Chrysalis an army.
* ''FanFic/ShadowsAwakening'': [[OurGhostsAreDifferent The Phantom]], as well as the other wizards who created the Shadowkhan, were once human, but the resulting magic of creating the lower, mindless Shadowkhan, caused them to transform (but since they kept their minds and became TheAgeless, they didn't care). [[EvilSorcerer Daolon Wong]] later repeats the process as a MidSeasonUpgrade.
* ''[[Fanfic/Experiment]]'': The inhabitants of Sezaria were all human once excluding the "original one" - Ladrafiefr/Kaito. Said inhabitants are now freaky aliens with tentacles coming from their backs.
* In the TranscendenceAU for GravityFalls, Dipper was his human self before he became a demon.
[[/folder]]

[[folder: Films -- Animated]]
* In ''Disney/BeautyAndTheBeast'', the eponymous Beast was a human prince with a cold heart who was turned into a chimera-esque monster by a sorceress posing as an old woman seeking shelter. The only way for him to break the curse placed upon him was to learn to love another.
* In ''{{WesternAnimation/Brave}}'', an old witch with a strange penchant for bears has at least twice given people "solutions" to their problems that involve turning people into bears. One such transformation resulted in [[spoiler: Mor'du, the demon bruin, who having asked for the strength of ten men seems to have taken heartily to his new identity as a complete monster.]]
* In ''WesternAnimation/RiseOfTheGuardians'', while all the Guardians are more supernatural beings than monsters, Tooth implies that they were all mortal before becoming who they are now. [[spoiler: Jack was a human who had drowned before the Moon transformed him into an immortal being.]]
[[/folder]]

[[folder:Films -- Live-Action]]
* In the horror film ''Film/TheCave'', one of the monsters bears the same tattoo on its hand as one of the cavers previously seen entombed within the cave system at the beginning of the movie. [[spoiler: Which bodes poorly for parasite-infected expedition leader Jack.]]
* [[spoiler: The Reavers]] in ''[[{{Firefly}} Serenity]]''. [[spoiler:Actually, it was BECAUSE their minds were warped that their bodies are so messed up (self mutilation).]]
* The Cenobites in ''Franchise/{{Hellraiser}}'' films. (And when a Cenobite is killed, his or her body turns back into human form, suggesting that killing one of them may be a MercyKill in some cases.)
* In the 1973 thriller b-movie ''Sssssss'', mad scientist Dr. Carl Stoner (Strother Martin) turns his lab assistants [[spoiler: into king cobras.]]
* [[StarWars Darth Vader]] probably qualifies, certainly in spirit: ''He's more machine than man now, twisted and evil.''
** General Grievous certainly does... well, he was Once A Kaleesh, but you get the idea.
* The lizard-monster in ''Film/TheRelic'' is revealed at the end to be a human explorer who ate a concoction of some particularly funky herbs in South America.
* Davy Jones in the second and third installments of ''PiratesOfTheCaribbean''. Lampshaded by Calypso, who describes Jones in this manner (and is responsible for the curse that transformed him). His crew of mutated humanoid sea creatures also qualify.
* The mutants in the ''Film/{{Doom}}'' movie. Condemned criminals who were injected with an extra pair of chromosomes, but due to their DNA having "genetic markers for evil", horrifically mutated. And they can sense who else has the same evil genes, so they attack them as well.
* Freddy Krueger from the ''Franchise/ANightmareOnElmStreet'' movies was once a human {{serial killer}}, but turned into something resembling a nightmare ghost/demon after his death.
* Jason Voorhees from the ''Franchise/FridayThe13th'' series was once a normal child, birth defects not withstanding. Then he drowned in a lake while camp counselors neglected their duties to have sex in the woods. Now, he's an undead killing machine, slaughtering anyone unlucky enough to come to Camp Crystal Lake.
* Vlad Tepes from the 1992 movie ''Film/BramStokersDracula'', apparently forsaking God turned him into a bloodsucking beast with power to turn others into vampires just like him.
* ''Film/LostInSpace'': This fate happens to Doc Smith in the future timeline, when he is infested/mutated by spiders.
* In ''Film/{{Phantasm}}'', inventor Jebediah Morningside steps through his newly created dimensional gate. [[HumanoidAbomination The Tall Man]] is what comes back through.
* The Son'a in ''Film/StarTrekInsurrection''
* ''Film/ThreeHundredRiseOfAnEmpire'': According to Queen Gorgo, Xerxes literally discarded every human part of him to become a God-King by [[DealWithTheDevil making a deal with evil forces]] in a desert cave.
* ''Film/DraculaUntold'', shows how Vlad III was before he was a vampire and his transition into the legendary Count Dracula.
[[/folder]]

[[folder:Literature]]
* The quote from the top of the page (now on the quotes page) is from ''The Beast in the Cave'' by Creator/HPLovecraft, written at some point around 1908. Similar themes can be found in ''The Rats in the Walls'', ''Facts Concerning the Late Arthur Jermyn and his Family'', and ''Literature/TheShadowOverInnsmouth''.
* Pech in ''Literature/TheDarkElfTrilogy'' technically was never human, but he was a harmless sentient creature turned into a monstrous hook horror by a wizard.
* Creator/JRRTolkien's Middle-Earth (''Literature/TheLordOfTheRings'', etc):
** As individuals, there are the Nazgűl (once human rulers) and Gollum (once just an ordinary proto-hobbit). In Tolkien's concept, evil and the various {{Big Bad}}s cannot create, only pervert: therefore, almost every evil creature (e.g. those used as {{mooks}}) is a corruption or mockery of a pre-existing being. The [[OurOrcsAreDifferent orcs]] are descendants of elves twisted by Sauron's predecessor, Morgoth. If you really want a {{squick}}y thought, it's rumoured that the Uruk-hai were partly Man in some fashion. Trolls are a mockery of Ents. Subverted in the case of the undead Barrow-wights, who only possessed the dead bodies of those buried. (However, the orcs-from-elves theory is only one possible explanation - Tolkien [[FlipFlopOfGod kept revising that one]]. Some dislike the idea that orcs were literally corrupted elves as that would imply the orcs have genuine sentience and intelligence, which Tolkien implies on a few occasions is not the case, so some suggest the orcs are corruptions of various non-sentient animals.)
* In ''Literature/TheRelic'', [[spoiler: the museum beast is revealed to be a scientist mutated by an ancient retrovirus]].
* In William King's ''TabletopGame/{{Warhammer 40000}}'' novel ''SpaceWolf'', Ragnor is most horrified about the nightgangers that they find in a [[{{Mordor}} Chaos-tainted cave]] because they, or their ancestors, had been human once.
** In Lee Lightner's ''Sons of Fenris'' when the Space Wolves and Dark Angels go up against Cadmus's elite forces, the tattered remnants of their uniforms is the only evidence they had once been human; some still wield weapons, but only those merged with their flesh.
* In Creator/GrahamMcNeill's ''TabletopGame/{{Warhammer 40000}}'' ''Literature/{{Ultramarines}}'' novel ''Dead Sky Black Sun'', Uriel realizes the Unfleshed -- monstrous, gigantic (next to him, a SpaceMarine), and flesh-eating -- were once not only human but [[spoiler:[[ChildrenAreInnocent children]]. When they are willing to speak with him, having [[TheNoseKnows smelled that he came from the same place they were made]], he finds that they are still good and will help him in [[TheQuest his quest]]. One sadly confesses to him that they loathe themselves because of their forms. In ''The Killing Ground'', Uriel must MercyKill the last survivor and is left deeply melancholy thereafter.]]
* In JamesSwallow's ''TabletopGame/{{Warhammer 40000}}'' ''[[Literature/BloodAngels Red Fury]]'', the Bloodfiends have fragmentary [[GeneticMemory memories]] of the Blood Angels whose [[BloodMagic blood they have drunk]]; Rafen, fighting one, is reminded of his dead mentor Koris, and when he kills it, its last breath [[DyingAsYourself might have been a word]]: Brother.
* Gav Thorpe's ''TabletopGame/{{Warhammer 40000}}'' novel ''The Path of the Warrior'' reveals that Eldar Exarchs were once Eldar, but lost themselves in the struggle to control their rage and became part of a gestalt consciousness dominated by the first Exarch to lead their shrine, trapped and unable to die, subsumed into the whole, and speaking only in stream-of-consciousness.
** This has actually been part of the background fluff for Eldar since the beginning. ''The Path of the Warrior'' simply gives us a very up close and personal exposure to what it's like inside the head of an Exarch.
* In ''StarWars: NewJediOrder'', the mindless warbeasts known as the Vagh Rodiek were once Rodians. They were created when the planet fell to the Yuuzhan Vong.
** Abeloth. She was once a mortal woman (species unclear) who served [[StarWarsTheCloneWars The Father, The Son, and The Daughter]]. She was eventually promoted to The Mother and loved her new family. As she aged, she grew paranoid that her ageless family would abandon her, so she drank of the Font of Power and bathed in the Pool of Knowledge. While this granted her immortality and advanced Force powers, this also mutated her into an EldritchAbomination. Sadly, this event caused her family to abandon her.
* In Neal Shusterman's ''Literature/{{Everlost}}'', the monster called the [=McGill=] is revealed to have been [[spoiler: Mary's brother, who sank down to the center of the earth and clawed his way back up. When he returned, he was a monster.]]
* The Steel Inquisitors of ''Franchise/{{Mistborn}}'' are humans who have been transformed into nigh-immortal killing machines via the dark art of [[BlackMagic Hemalurgy]]. [[spoiler: The [[AlwaysChaoticEvil Koloss]] from the same series were originally humans as well, created by a similar process.]]
** Also [[spoiler:The First Generation of kandra were ALSO former human Feruchemists who were friend of the Lord Ruler before his ascension, the other kandra are descended from mistwraiths that were ALSO Feruchemists, who weren't friends of the Lord Ruler and so didn't get to be sentient after the Lord Ruler was done with them. Kandra are made from mistwraiths using the same BlackMagic that makes Inquisitors and koloss.]]
*** Unusually for these tropes, it's not all that horrifying or morally dark. [[spoiler: Kandra are intelligent and have no memories of being human, except for those of the first generation, so it's not traumatic for them. The BlackMagic that turns mistwraiths into kandra is "black" because it is BloodMagic, sort of, and turns them into TheMole for the BiggerBad, but that part doesn't come up until the end of the last book of the trilogy.]]
* In ''Death Masks'' of ''Literature/TheDresdenFiles'', Harry gets a nice shock to the system when he looks into the eyes of the latest monstrosity to cross his path and [[spoiler:sees the human soul it has.]]
** In ''Cold Days'' at the end, [[spoiler: Queen Mab tells Harry that she was once a mortal. And Molly fills this as she becomes a Fae Queen as well.]]
** And then there are also the [[OurVampiresAreDifferent three types of vampires]]: those of the Black and Red Courts are created in the typical way (humans turned through blood-drinking/exchange), while the White Court are born as humans (from other White Court) then turn into vampires sometime during their late teens/early adulthood.
* Played with in ''Literature/{{Discworld}}''. Unseen Academicals marks the first appearance of [[spoiler: orcs]] in the series. During the course of the book it is revealed that they are a manufactured species made from [[spoiler:goblins. Only as it turns out, that's a misconception. As Vetinari puts it, "Goblins wouldn't have been nearly as ferocious." [[HumansAreBastards Discworld orcs were made from men]].]]
** Also, the librarian (due to a massive magical event). He's perfectly happy being an orangutan for the rest of his life; [[BerserkButton just don't call him a monkey]].
* In Creator/RobertEHoward's ''ConanTheBarbarian'' story "Literature/RedNails", Tolkemec.
-->''He was not mad, as a man is mad. He had dwelt apart from humanity so long that he was no longer human.''
** Also, Thak from "Literature/RoguesInTheHouse." It's unclear whether he degenerated from humanity into his apelike form, or whether he ascended from apedom into something resembling humanity.
** The EldritchAbomination in ''Literature/BlackColossus''.
* In the ''Literature/GauntsGhosts'' novel ''His Last Command'', [[spoiler: the stalkers are Guardsmen and ogryns captured by Chaos and reshaped into beasts.]]
* In Pat Murphy's ''Literature/ThereAndBackAgain'', Rattler, the cyborg Gollum-equivalent, was human until the Resurrectionists started experimenting on her.
* All the monsters having once been human is a major theme and source of conflict in the ''FelixCastor'' novels.
* In Terry Brooks' ''Literature/TheWordAndTheVoid'' series, [[OurDemonsAreDifferent demons]] are former humans who gave up their souls for power.
* A brief part of Creator/GarthNix's ''Literature/OldKingdom'' series followed some sort of undead/free magic creature that used to be human.
** Most of the various types of Dead were originally human in body and/or spirit (though some of the weaker ones, like the gorecrows, were once animals). [[TheDragon Hedge]] starts out as a human necromancer, but becomes progressively inhuman as the Destroyer's power over him increases (thankfully, we never learn what exactly he was turning into, though it doesn't seem to have been Dead).
* GodEmperor of ''{{Dune}}'' Leto II (mostly internally or to those close to him) laments his loss of humanity after becoming a giant {{sandworm}}, but he knows this is necessary for the survival of the human race.
* Used in the Series/{{Angel}} novel "Image", which has a guy who once was human but became more and more demon (and grotesque) in order to stay alive for hundreds of years.
* Creator/IsaacAsimov in his story "Eyes Do More Than See".
* ''Literature/HaloPrimordium'' by Creator/GregBear is narrated by the prehistoric human Chakas, now an AI more than 100,000 years old, and on his deathbed. At the end of ''Primordium'', the AI's name is revealed: [[spoiler:[[VideoGame/HaloCombatEvolved 343 Guilty Spark, the Monitor of Installation 04]].]]
* ''Literature/LegacyOfTheDragokin'': Jihadain can transform humans and other beings into monsters and [[TheVirus one bite transforms their victim into the same kind of monster.]]
* Subverted in ''Literature/TheIslandOfDoctorMoreau'': the narrator thinks that Moreau's creations are transformed humans, but they are actually animals that Moreau has turned into {{Beast M|an}}en.
* ''Literature/DrFranklinsIsland'', inspired in part by the above entry, has a couple of teenaged girls transformed into mutant animals. They grow used to their new forms before too long, but are always aware of what they look like to others. One of the scientists, face to face with one for the first time since she woke up like this, is struck with horror and hopes out loud that she doesn't have the same mind.
* The Rainmaster, a unique, acid rain-spawning undead horror in ''Literature/DiamondSwordWoodenSword'' is a former human wizard from the order of Arc, cursed by the Black Sword of Humankind. The same curse also afflicts his daughter Sylvia in later novels.
* Moryanas in ''Literature/SecretCity'' are the race of cute slender girls who can [[SuperMode shapeshift into musclebound, regenerating killing machines]]. While they reproduce sexually (they can interbreed with most of the races but give birth only to Moryanas, no matter who the father was), the first of them were artificially created from ''two'' human women each.
** Hiperboreans, or Kadath, draw their power from Golden Root, a drug that grants or boosts magical abilities, but is extremely addictive, and prolonged use causes mutations. Most of Hyerarchs of Kadath, the elite, do not even resemble men by now. However, several most powerful [[BishonenLine look completely human]] save for their SupernaturalGoldEyes.

[[/folder]]

[[folder:Live-Action TV]]
* Vampires on ''Series/BuffyTheVampireSlayer'', obviously. Also, one episode had Giles turn into a demon.
* Several of the monsters on ''Series/{{Supernatural}}'', the most important being the demons.
* One later iteration of the Daleks in ''Series/DoctorWho'' were produced by "filleting, sifting, and pulping" living humans to render a handful of cells judged strong enough to be shaped into Dalek form and welded into a travel machine.
** Another Dalek faction, the Imperials, were made from [[HumanPopsicle Human Popsicles]]. "Not pure enough in their blobbiness" indeed. And the original Daleks were once the humanoid Kaleds.
** The Toclafane are AxeCrazy flying metal spheres that are able to deploy knives and laserguns. [[spoiler:Turns out that they once were humans living at the time of the universe's end. They turned themselves into metal spheres in hopes of surviving the end of the universe.]]
** And of course the Cybermen, more than any of the others. It's arguably the whole conception behind the way they were originally written in the 1960s.
** In the revived series, the Cybermen all look identical and have the same voice, so it's particularly jarring when Pete Tyler is confronted by a Cyberman that used to be ''[[spoiler: his wife.]]''
** Many stories involving TheVirus: e.g., "Mission to the Unknown", "Inferno", and "The Seeds of Doom".
** Poor little Jaimie from "The Empty Child" / "The Doctor Dances".
** The Face of Boe may have once been [[spoiler:Jack Harkness, or maybe Jack was just messing with the Doctor, and Martha, when he said that.]]
** [[spoiler:Oswin]] in "Asylum Of The Daleks". [[spoiler:The Daleks turned her into one of them, and she was unable to deal with it, instead dreaming up that she was still human]].
* In ''Series/PowerRangersTimeForce'', Frax, the robot who worked for Ransik but would eventually go solo, was once a human named Dr. Fericks who saved Ransik's life in the past, but was rewarded with the destruction of his lab and body. After using his own technology to rebuild himself, Frax vowed revenge on Ransik, and infiltrated his organization to bring him down from within.
** Master Org in ''Series/PowerRangersWildForce'' was a Doctor before taking on the powers and identity of the original Master Org. His minions weren't happy when they found out, but he proved to be too much for them when they tried to rebel.
** Zeltrax was transformed into a cyborg after a lab explosion. He is ''not happy'' about the loss of his body, and has decided that it is (in a roundabout manner) Tommy's fault. Mesogog was once a human scientist too.
** In ''Series/PowerRangersSamurai,'' Deker and Dayu were once human. Dayu sold her soul to save the life of the then-human Deker, but Deker has lost his memory and is now a BloodKnight who fights to satisfy his bloodlust, either by defeating a WorthyOpponent or by being put out of his misery. [[spoiler: Last time he fought the Red Ranger, it looks as if the latter has finally happened. However, the season's only half over...]]
* All Borg in ''Franchise/StarTrek'' started as other species, usually humanoid.
** And Seven Of Nine is an actual human from the Federation.
* [[spoiler: The Man in Black]] on ''Series/{{Lost}}'' claims to have once been a human before becoming [[spoiler: a sentient cloud of smoke.]] He's now human again, only able to switch between his monster form and [[spoiler: John Locke.]] A flashback episode shows that this is true.
* In the cult OneEpisodeWonder series ''Series/HeatVisionAndJack'', the CoolBike Heat Vision used to be Jack's friend Owen, before he got hit with an experimental ray gun that caused him to merge with his motorcycle.
* The wicked Witches flying monkeys in ''Series/OnceUponATime''
* The "Oathkeeper" episode of ''Series/GameOfThrones'' reveals that [[spoiler:a good number of the White Walkers were originally Craster's sacrificed sons whom the Night's King transformed with a touch.]]
[[/folder]]

[[folder:Music]]
* The eponymous character in the Music/BlackSabbath song "Iron Man" was a well-intentioned human given metallic form by a "great magnetic field" while traveling time to save the future of humanity. He went on to [[spoiler:go cuckoo and decimate the human race]] because after he saves them, [[UngratefulBastard they won't help him or accept him]].
[[/folder]]

[[folder:Myth And Legend]]
* Most undead creatures are, naturally, like this. For example: zombies and vampires.
* In some [[GreekMythology Greek myths]], Medusa was a priestess who was transformed as punishment [[ValuesDissonance for being raped by Poseidon in Athena's Temple]] (Athena, pissed that sex was going on in her temple, but unable to actually do anything to Poseidon, opted to punish Medusa instead).
** Quite a lot of animals in Greek myth were actually humans who ticked off the gods and were transformed into beasts - Arachne and King Lykans being the two most prominent.
*** Scylla and Charybdis also fall into this category.
** For a full list, read Ovid's ''Metamorphoses''.
** Oddly subverted in the case of Heracles though. Born a man, his heroism leads him to be elevated to a god. Admittedly, one of his parents was a god, but there are plenty of other heroes in Greek mythology who have one divine parent, and Heracles is the only one who manages to become a god himself (though there are several humans who upon their deaths are made into constellations, trees, islands, stars, etc so that they will never 'die').
* [[NorseMythology Fafnir]], aka the dragon from Wagner's Ring cycle, aka the inspiration for Smaug in ''Literature/TheHobbit'', Was Once a Man! In fact, he got the gold hoard first, and it cursed him for his greed.
** His siblings, fyi, were a dwarf and an otter. No reason given.
*** His brother was a shapeshifter, as was he and his father, hence the otter thing.
[[/folder]]

[[folder:Toys]]
* [[spoiler: The Bohrok]] in ''{{Bionicle}}'' [[spoiler:were Once Av-Matoran]]. goes into NightmareFuel territory when you realize that Nuparu made the Boxor machines out of [[spoiler: Bohrok parts, so the Boxors are made out of [[HumanResources dead Av-Matoran]]... and are piloted by Matoran who use them to fight still functioning Bohrok. While he didn't pilot Boxors, one of the topmost fighters in the war against the Bohrok was Takua, himself an Av-Matoran!]]
** [[spoiler: [[SoylentGreen They're people]]. Boxors are people!]] Sorry, it had to be done.
[[/folder]]

[[folder:Tabletop Games]]
* A large number of ''TabletopGame/DungeonsAndDragons'' monsters qualify, such as vargouilles, [[{{Cthulhumanoid}} illithids]] (in which a larva eats your brain and uses your body as the foundation for its own), and skum (and pretty much all humanoid undead). A number of prestige classes, such as the alienist and fleshwarper, eventually become something inhuman as well (and not in a good way, like a monk's ascension to outsider status), although without necessarily being evil.
* In ''TabletopGame/{{Mortasheen}}'', this is the case with the Arthropoids, a class of creature made from humans fused with various type of insects ala ''Film/TheFly''. This also applies to several of the player races, like the [[{{Cyborg}} Borg]], the Sectillians and the Zombies.
* Chaos Spawn define this trope in both ''TabletopGame/{{Warhammer}}'' and ''TabletopGame/{{Warhammer 40000}}''. The [[EldritchAbomination Chaos Gods]] reward their champions with many gifts, including [[BodyHorror physical mutations]]. Champions rewarded with too many ill-considered gifts will eventually lose their sanity and become little more than beasts, herded into battle by their former followers.
** Special mention goes to Scylla Anfinngrim, a champion of Khorne who devolved into a giant, hairy, shambling clawed horror. Unlike most spawn, he's proven nearly impossible to kill, and his tribe keeps him fed and worship him as the mighty warrior he was in exchange for getting to take a pure killing machine to war with them.
** Also the horrific Tamurkhan from the Warhammer Fantasy supplement Tamurkhan Throne of Chaos. He was turned into a child sized maggot-like creature with multiple eyes [[PuppeteerParasite who can borrow into people's bodies and take them over to be his own]] [[BodyHorror while they're still alive]].
** Fabius Bile is shown pulling this on a large number of {{Space Marine}}s in the HorusHeresy novels. Only one or two retain some fragments of sanity after the mad Apothecary finishes tinkering; the rest are little more than rabid killing machines.
** The Necrontyr were once a sentient organic species, but long ago had their consciousnesses uploaded into robotic bodies, becoming the Necrons. Among other things, this cost them their souls, which were devoured by their gods. Some Necrons have further afflictions: the relatively simplistic method that was used to transfer most of the civilians into their bodies left them as little more than automatons, while the Flayed Ones have been driven mad by the loss of their mortal bodies, and seek to recapture the sensations of life by garbing themselves in the flesh of the living.
** The [[MadScientist Haemonculi]] [[MadArtist fleshcrafters]] turn some of their prisoners into Grotesques, massive hypertrophied ''things'' with iron plates [[TheBlank fused over their faces]] and weapons grafted into their limbs. They are treated as CannonFodder in battle, and frequently used against their own species. Given how the Dark Eldar feed on physical and emotional anguish, it is quite likely that Grotesques retain their original minds but are [[AndIMustScream trapped in bodies no longer under their control]].
*** For an extra dose of NightmareFuel, we have the Wracks, Dark Eldar who willingly let a Haemonculus turn them into lesser Grotesques. Some of them treat this as an apprenticeship, hoping to become Haemonculi themselves, but many are just bored with their decadent lives and ''want'' to spend decades as horrific abominations.
* Your ''player characters'' qualify as this in Creator/{{White Wolf}}'s ''TabletopGame/ChangelingTheLost'' for the TabletopGame/NewWorldOfDarkness. Each and every changeling was once a human man or woman, until the day that [[TheFairFolk The Gentry]] stole him or her away to {{Arcadia}}. There, they slowly lost most of their humanity and became bizarre faerie creatures themselves. The ones who managed to trick, sneak or fight their way back to Earth are the lucky ones; they still have something of a human mind left. Others remain in Arcadia until there's nothing human left -- there's only the faerie. Even those lucky escapes aren't really human, physically, they're just wearing an illusionary cloak of being human called the Mask. And their mind is still rooted in Arcadia's madness, so they're slowly becoming less and less human mentally, anyway.
* In ''TabletopGame/GeistTheSinEaters'', the titular Geists are alien and horrifically inhuman monsters. Except, really, they're actually very old human ghosts who have fused with an AnthropomorphicPersonification of death.
[[/folder]]

[[folder:Video Games]]
* All of the [[spoiler:Feldragons]] in ''VideoGame/ArcRiseFantasia'' are heavily implied to be people of the [[spoiler:Divine Race]] exposed to hozone without a [[spoiler:dragon gem]] to protect them. Those that aren't [[spoiler:Divine Race turned dragons]] are implied to be the results of Ignacy's experiments on [[spoiler:Common Race people]], including orphans.
* VideoGame/DarkSouls and VideoGame/DemonsSouls are made of this. Pretty much every hollow you ever face is a human that gave up [[HeroicBlueScreenofDeath hope]]. Not only that but many of the bosses and all the black phantoms also qualify. Poor Artorias.
* Crewman Norris in ''VideoGame/ShinMegamiTenseiStrangeJourney''. He begins hearing voices as you begin exploring Sector Bootes, and then he reaches for the sector's central tower, the [[IDontLikeTheSoundOfThatPlace Palace of Pleasure]]. Next time you see him, he's being experimented upon, [[BodyHorror and the transformation ain't pretty]]. Worst part is, [[NightmareFuel you can see how he slowly loses his mind as you traverse the sector]].
** From the same company, [[VideoGame/ShinMegamiTenseiIIINocturne the Hito-Shura]]. OrdinaryHighSchoolStudent one moment. Godslaying BadAss HumanoidAbomination the next. Despite relatively few physical changes (only a horn in the back of the head and glowing full-body tattoos) WordOfGod is his entire body has become a demon's - the horn is actually a primitive brain or sensory organ allowing him to truly interact with demons, and the tattoos are actually subdermal streams of demonic lymph.
* Virtually all the monsters from the ''Franchise/ResidentEvil'' series (with the exception of a few based on animals) are humans infected with various viruses or parasites.
* The ghouls in the ''VideoGame/{{Fallout}}'' series. Apart from looking like corpses, they're not really very different from humans (they're more resistant to some drugs and they may live much longer), but some go mad, becoming [[OurZombiesAreDifferent Fast Zombie]]-esque "Feral Ghouls". Super Mutants are an even straighter example, as they [[TheVirus actively kidnap humans to infect]] with the FEV (Forced [[EvilutionaryBiologist Evolutionary]] Virus).
** A specific mutant in ''VideoGame/{{Fallout 3}}'' actually says word-for-word "I was once a man" [[spoiler:but he's referring less to his mutation and more to his being fused with a tree.]]
** [[http://www.youtube.com/watch?v=810JiQQ7G-w#t=1m24s These things look - I think they really used to be people]].
* ''Franchise/DeadSpace''. Every single enemy you fight was once a human; even the significantly larger bosses are made of dozens or even hundreds of human corpses joined together into one big mass. The Lurkers are encountered just one room after a datapad with a list of the month's births, confirming that yes, these were somebody's babies before they were murdered and transformed, just like the grown-ups.
** The sequel introduces the Pack, a form of zombie made from prepubescent children who hunt in groups.
* ''VideoGame/CityOfHeroes'' has several, notably the Devoured, [[spoiler: the Hamidon, the Rikti, and as you find out in one story arc, Malta's Titan robots.]].
** [[spoiler: The Hamidon]] is definitely the worst case, being [[spoiler: a giant BlobMonster]].
*** [[spoiler: Giant BlobMonster]] doesn't do it justice. It's [[spoiler: an amoeba the size of a city block, created through some terrible fusion of genetic engineering and dark magic, with maybe some divine empowerment thrown in. EldritchAbomination comes to mind.]]
* An in-universe theory toward the Thorn bloodline of ''BloodlineChampions''.
* This is fairly common in the ''VideoGame/{{Warcraft}}'' universe. Notable is the Demon Hunter Illidan Stormrage, who, after using a demonic artifact to gain power, was transformed into a demon.
** Illidan's got nothing on, well, every race on Azeroth AND beyond. Firstly, those that play it straight:
*** Naga used to be [[OurElvesAreBetter Night Elf]] [[BlueBlood Highborn]] who were [[ScaledUp transformed]] by their queen, Azshara, when their city was sunk into the sea during [[EarthShatteringKaboom the Sundering]].
*** The Broken, the Lost Ones, and the Eredar are all degenerated versions of the Draenei who were [[BodyHorror mutated]] by over-exposure to fel energy.
*** The Forsaken were the humans who were stricken with a plague of undeath.
** ''VideoGame/WorldOfWarcraft'' also [[InvertedTrope inverts]] this when we discover that [[spoiler: the Curse of Flesh caused mutation in many, if not all, of the Titan's creations. Earthen became dwarves, mechagnomes became regular gnomes, and Vrykul became Humans]]. These are all inversions since the transformations go from "monster" to man.
** There is a theory that Night Elves (from which all other elves are descended) descended themselves from Trolls who were exposed to the arcane energies of the Well of Eternity, once more inverting the trope.
** All but a small few of the demonic races were once regular beings that became so tainted by fel energy they eventually became full demons, usually caused by direct interference by the Burning Legion as an assimilation plot. Many night elves became full demons in the form of satyrs and many other races became part-way demonic such as chaos orcs and the felblood elves through similar corruption. The eredar are an odd case because the majority of the species became demons after siding with the Legion while a minority fled and became draenei, which is different because the previous cases had mainly the minority of their race become demonic.
*** Only a few races like the Nathrezim are confirmed to be originally demonic.
* In ''Franchise/{{Halo}}'': Captain Keyes, when you eventually find him. He's been ''absorbed'' into a massive Flood organism, [[AndIMustScream retaining enough sentience]] to contact you on your commlink through sheer force of will. Not to mention the fact that the Master Chief needs his neural thingywhatsit, requiring him to punch through ''what was left of his face into his brain''. Hell, any human (or Covenant, if you consider alien races) that the Flood infects could be considered an example of this.
** In ''{{VideoGame/Halo 4}}'', [[spoiler:we find out that most of the Promethean Knights used to be human, who were harvested by the Didact to be made into weapons.]]
* Scorpion, from the ''MortalKombat'' series, was once Hanzo Hasashi, the leader of the Shirai-Ryu clan of ninjas. When their rivals, the Lin Kuei, slaughtered them, and their leader Sub-Zero killed him, he returned as a wraith fueled by a burning desire for revenge.
* Most, if not all, of the monsters from ''VideoGame/CliveBarkersJericho''.
* Kokiri are said to turn into the race of skullkids when lost. They're usually shown as more tragic enemies, you being able to talk with them as a child in ''VideoGame/TheLegendOfZeldaOcarinaOfTime''.
** The same game mentions that Hylians would eventually be transformed into Stalfos when lost in the woods. Just as creepy, given that you actually ''meet'' a lost man in the woods who appears oddly gaunt and skeletal, and when you return from his fetch quest with what he wants, he's gone, and a Stalfos is waiting for you.
** All the [=NPCs=] in the Dark World of ''VideoGame/TheLegendOfZeldaALinkToThePast'', as the Dark World has the effect of transforming anyone who enters it into a form that matches his personality. Link, who in this game is apparently a coward who must overcome his fear, is transformed into a pink bunny rabbit without any means of protecting himself.
** Similarly, the Twilight in ''VideoGame/TheLegendOfZeldaTwilightPrincess'' turns normal humans into spirits, Link into a ''wolf'', and does not seem to affect magic-users. Spirits (and Twili) will eventually transform into the inconsistently named "[[TheHeartless Twilit Messengers]]" (better known as "those screaming things that guard portals").
*** Even better known as [[GoddamnedBats 'Those Bastards Who Sound Like The Iron Giant Being Beaten To Death And Refuse To Stay Dead For More Than Five Seconds']].
*** Described by the LetsPlay/FreelanceAstronauts as "Rastafarian squid-dudes".
** Though they aren't actually monsters, [[spoiler: [[VideoGame/TheLegendOfZeldaTheMinishCap Ezlo]] and [[VideoGame/TheLegendOfZeldaTwilightPrincess Midna]]]] probably count.
* Done in at least two side quests in ''VideoGame/FinalFantasyTacticsA2''. In one mission, a requester asks for help as he and his friends are trapped in a mine and is afraid he will become the ghosts that haunt the place. When you get there, you encounter a gang of ghosts and [[TearJerker its leader weakly begs for help]].
** In another mission, a requester asks for a Potion and Hi-Potion to treat some wounds/fatigue. When you meet the person, it's actually a zombie, but has retained enough sense and control to talk to Luso normally. When the zombie uses the Potion on itself, [[ReviveKillsZombie it winds up hurting itself]] and Luso has to stop it from drinking the Hi-Potion. That's when the zombie realizes it is dead and was wondering why clans were attacking and people at inns throwing rocks. Later on, you discover that the zombie is actually [[spoiler: Frimelda, a former Blademaster. She fought battles with a Paladin and over time, he grew jealous of her success as a fighter while he failed to follow in her footsteps, so he drugged her and she became a zombie. You can heal her eventually and she will join your clan]].
** One of the gifted somehow turned into a dragon, originally being a hume.
* In ''VideoGame/GoldenSun'', the people of Bilibin wanted to build a castle out of wood for their queen. The tree that they put their axes into turned out to be sentient, and cursed all of the villagers of Bilibin and Kolima to turn into trees. Fortunately, this gets undone after his HeelFaceTurn.
** Hooray, we defeated the dragons! [[BalefulPolymorph Wait]]... [[AlasPoorVillain oh]], ''[[PlayerPunch crap]]''.
* Necrid in ''SoulCalibur 2''
-->'''Talim:''' What ''are'' you? ...you're human, aren't you?
** And for crying out loud, [[BigBad Nightmare.]]
*** Subverted in the next game, when [[spoiler: Siegfried is human again, and his [[AnimatedArmor armor]] lives on as the new Nightmare.]]
** And, of course, Lizardman.
** Raphael becomes infected with Soul Edge's evil and becomes some sort of vampire-like entity.
** Cervantes as a one time wielder of Soul Edge has been twisted into a ghost/zombie pirate.
*** Subverted in ''SCV'', when he becomes human once more.
** Charade and ''SCII'' Berserkers also count.
** Algol is another example.
** Don't forget Tira, who became a Malfested thanks to Soul Edge.
* Not literally a 'man' but close enough, Scorpiton from ''VideoGame/{{Patapon}}''. He actually is [[spoiler: Makoton, who sold his soul to a devil to avenge Aiton, a Zigoton you killed during the first half of the game.]]
* Dr. Nefarious from ''Franchise/RatchetAndClank'', and despite the fact that he was once human, he ''hates'' humans with a passion, calling them "squishies" and other derogatory names.
* Stalkers in ''VideoGame/HalfLife2'' are humans taken prisoner by Combine forces for acts of rebellion or "simply being in the wrong place at the wrong time", according to Alyx. Their organs and genitalia are removed and their blood replaced with a saline solution, a metal plate welded over their "face" and a strong implication that they are rewarded for good behaviour with artifical limbs so that they can ''walk''. [[NightmareFuel Brrr.]]
** For that matter, the Combine soldiers themselves were once humans who have undergone ''[[FakeMemories memory replacement]]'' and had most of their organs replaced with [[CyberneticsEatYourSoul cybernetic implants.]] The soldiers rise in rank by giving up more and more of their humanity. It's implied that all of the Combine's bio-weapons had similar origins.
* ''VideoGame/FinalFantasyX'' does this a lot. All the Aeons were human, and an optional superboss is a monk named Omega whose hatred of [[spoiler:Yevon]] turned him into a gigantic, four-legged monster with the power to create novae.
** The most [[NightmareFuel Disturbing]] / [[TearJerker Saddest]] example however is Anima, who not only looked monstrous (a chained, gap-mouth giant corpse rising out a shell) but is [[spoiler: [[SmugSnake Seymour]]'s human mother, who basically had turned herself into one to give him the ability to return to his father's people. Now she rages at how evil he became.]]
** The fiends you fight in random encounters were once human souls. In fact, in the cutscene where the party reunites with Yuna in Home, you can see fiends forming from the souls of recently killed InnocentBystanders in the background. And, of course, to top it all off, there's [[spoiler:Sin, aka Jecht]].
* Pretty much everybody in ''VideoGame/NexusWar'': Demons, angels, undead, and several others. All were once human and have become utterly inhuman. Just about the only characters that ''don't'' fit this trope are Eternal Soldiers.
* ''StarCraft'''s Infested Terrans, which are a lot more open about it (since they're named, well, "Infested Terrans"). They're still horrific abomination suicide bombers, though.
** In ''StarCraftIIWingsOfLiberty'', an even more mutated form called "Aberrations" appears in a few missions. These get upgraded to a controllable unit in ''StarCraftIIHeartOfTheSwarm''.
*** Also from ''Heart of the Swarm'', the unique Zergform Izsha, who serves as Kerrigan's equivalent of an adjutant and who can be charitably described as a "chitin-plated naga with claw-tentacles for hair", is eventually revealed to have been a Terran woman, a medic named Amanda Haley, who was mutated into this new form by the Queen of Blades when she sensed the woman's psionic potential.
* In ''VideoGame/QuakeII'' and ''VideoGame/QuakeIV'', the majority of the enemies you face are people who have been captured and [[YouWillBeAssimilated forcibly turned into cyborgs]]. Some aren't even turned into troops, they just get their limbs hacked off and used as ''scenery'' (but they still twitch and bleed when shot). In ''Quake IV'', this happens to the ''player character'', and [[NightmareFuel you get to see it happen, from his point of view]]. [[http://www.youtube.com/watch?v=3clVvh5gbGE&feature=related Curious?]]
* In ''VideoGame/KnightsOfTheOldRepublic'', rakghouls all used to be human before being [[ViralTransformation bitten and infected]]. The player gets to meet some Outcasts and a terrified Republic soldier before they transform. Other parts of the EU use the rakghouls again, only this time there's a deranged Dark Jedi with a talisman that instantly transforms non Force-Sensitives into them. An old clone trooper [[HeroicWillpower holds out longer than most]], but doesn't quite manage to kill her.
** Also invoked to describe the unusual nature of Darth Nihilus. Although he's been implied to be a NegativeSpaceWedgie, or even the hero's EnemyWithout. All depends on who you listen to.
* Although not originally human, Sonic's were-hog form in ''VideoGame/SonicUnleashed'' can be an example of the original mind/new body version.
** The Archie comics give us a much straighter example in Jules.
* Many ''{{Neopets}}'' characters like Edna the witch (now a green Zafara) and the Island Mystic (now a yellow Kyrii).
* Rapture's Big Daddies are revealed to be this in ''VideoGame/{{BioShock|1}}''.
* In ''VideoGame/BlazBlueCalamityTrigger'', [[spoiler: Arakune]] was once a person. Litchi hopes [[IKnowYoureInThereSomewhereFight the original personality is still in there]], but it [[LaserGuidedAmnesia doesn't seem to remember its previous life.]] [[spoiler:Then it says her name...]]
* The trope's name was used word-for-word in ''VideoGame/PrinceOfPersiaTheTwoThrones'' by the Prince to describe the giant, jawless boss he has to fight. And just like said boss, most of your enemies from the first and third game from the series are this.
* The Many in ''SystemShock2''. It's really unnerving to having your enemy viciously assault you while screaming for you to run away or put them out of their misery.
* ''VideoGame/SilentHill3'', possibly. [[spoiler:"They look like monsters to you?"]]
* ''Franchise/DragonAge'' has the werewolves, more progressive ghouls, Broodmothers [[spoiler:(who were, rather, once women)]], and Golems [[spoiler:(who were living dwarves forged into stone soldiers by [[NightmareFuel pouring molten lyrium through their eyes and mouth before hammering and chiseling them into the proper shape]])]].
** Also, if the Chantry's teachings are true, the first Darkspawn were this.
*** The ''VideoGame/DragonAgeII'' DLC ''Legacy'' [[spoiler:confirms them. The final boss of ''Legacy'', the Awakened Darkspawn Emissary Corypheus, was one of the original Tevinter Magisters who tried to claim the power of the Golden City.]]
* Not truly a monster, but in ''VideoGame/ChronoTrigger'', Frog used to be a human knight until being cursed with his current form. [[CursedWithAwesome He doesn't let it get to him anymore]].
* TheHeartless and the Nobodies of ''KingdomHearts'' are composed of [[AnatomyOfTheSoul different parts of souls of people]]. While most are mindless, some retain enough sentience and knowledge of their past lives to lament their fate.
* ''VideoGame/DawnOfWar: Dark Crusade'' invokes this with Macabee, an archaeologist who awoke things best left undisturbed and was turned into a Necron Pariah. When another race assaults the Necron stronghold, Macabee notes "I was like you, once, clinging to life and blind to the truth... deep in these catacombs, I was remade..."
* In the ''VideoGame/{{Diablo}}'' games, Humans possessed and altered to fit their shape by the Prime Evils, through DemonicPossession. Diablo's body turns back into that of the young prince in the first game when he's killed, and in ''VideoGame/DiabloII'', all the [[BigBadDuumvirate Three Evils]] are in the bodies of possessed humans, which turn more and more monstrous in irregular stages.
* ''VideoGame/ParasiteEve2'' is a more nightmare fueled version than usual: every single one of the monsters in the game [[spoiler: were people who worked on the "Second Neoteny" project]], which was a project intended to transform large numbers of humans into monsters. [[spoiler: Humans who VOLUNTEERED for the project.]] This makes the monsters even more horrifying, since [[spoiler: once your attention has been called to it, you can easily see how they were altered from their original human form.]]
** Made even worse when it is revealed [[spoiler: they used the Heroine's DNA to make start the process to begin with. So even the monster-part came from a human as well.]]
* In ''VideoGame/WarioLand 3'', [[spoiler: all the monsters in the game were humans transformed by the Hidden Figure.]]
* ''VideoGame/PokemonBlackAndWhite'' has the Ghost Pokémon Yamask (and, by extension, Cofagrigus), whose mask is its face from when it was human. Its Pokedex entry states that [[TearJerker 'it sometimes looks at its mask and cries'.]]
** In a similar manner to the Legend of Zelda examples above, ''Videogame/PokemonXAndY" gives us Phantump, who, according to the Pokédex, is formed when the spirit of a child who died after getting lost in a forest possesses a tree stump.
* ''PhantasmagoriaAPuzzleOfFlesh'' reveals that [[spoiler: the Hecatomb was a human being[[note]]To be more specific, the ''real'' Curtis Craig[[/note]] that transformed into a monster - one that retains only vaguely human-like characteristics]].
* The Black Knights in ''ElevenEyes'' underwent an EmergencyTransformation courtesy of Misao. As Misao is the only one of them technically ''alive'', she's also the only one that can change back. It doesn't help that they're wearing the monsters of the Red Night as a sort of living armor.
* In ''VideoGame/KingsQuestVI'' the Lord of the Dead was a man long ago, chained to the throne of the Underworld and enslaved as its ruler. The throne and his witnessing of unending tragedies slowly drained away the man's humanity and transformed him into something beyond comprehension.
* In ''VideoGame/DragonQuestIX'', [[spoiler: the entire Gittish empire.]]
* In ''VideoGame/{{Portal 2}}'', it's revealed that [[spoiler: [=GLaDOS=] is less of an artificial intelligence and more of a human one; having been the product of BrainUploading the consciousness of Cave Johnson's secretary, Caroline, into a computer intended to house Cave's.]]
* In ''[[VideoGame/{{Infamous}} inFamous 2]]'', [[spoiler: the swamp monsters]] were once humans, transformed by [[spoiler: Bertrand]]. [[spoiler: Bertrand]] himself can also change into a gigantic monstrous form.
* In the Game Boy Advance and PSP versions of ''VideoGame/FinalFantasyIV'', Cecil's trial in the BonusDungeon includes a potential encounter with a Goblin who insists that he used to be human, and that the curse on him will wear off shortly. Indeed, if you don't attack him, the battle automatically ends and a man is standing where the Goblin was (killing the Goblin causes Cecil to fail that part of the trial, of course.)
* In ''VideoGame/{{Super Robot Wars Z}}2: Hakai-hen'', The Dimesional Beasts [[spoiler: are people who were fused with their mecha by Gaiou. TheReveal comes in [[http://www.youtube.com/watch?v=sTPWJABzfEYscenario 49]].]]
* All of the main characters in ''VideoGame/FinalFantasyXIII'' are normal humans who were turned into l'Cie (servants of fal'Cie, the providers for Cocoon/Gran Pulse), which grants them strength and magical powers, as well as resulting in them being ostracised by the people of Cocoon. Also, it is revealed early on that any l'Cie who fail their task are turned into Cie'th, deformed crystal-covered monsters who wonder the world until they eventually lose their will and turn to stone. And even then they are still alive, and [[AndIMustScream awake and suffering.]]
* Version 6 of ''VideoGame/AoOni'' has all three of the four main characters converted into one of the monsters when they were killed.
* At the end of ''VideoGame/MagicalGirlLyricalNanohaAsPortable: The Gears of Destiny'', [[spoiler:the Unbreakable Darkness, the EldritchAbomination that the cast had been fighting against for the entire game]], is revealed to have once been a human named Yuri Evelvine.
* ''Franchise/TheElderScrolls'':
** ''VideoGame/TheElderScrollsIIIMorrowind'' has the ash and corprus creatures. The former have been twisted by the magic of [[BigBad Dagoth Ur]] into {{humanoid abomination}}s and the latter are infected with the corprus disease, slowly turning them into leprous zombies.
** ''VideoGame/TheElderScrollsVSkyrim'' has the Falmer, former Snow Elves who after losing a war against humans sought refuge with the Dwemer, [[OurDwarvesAreDifferent a technologically-advanced race of underground elves]]. Despite their early hospitality, the Dwemer suddenly turned on and enslaved their kin, feeding them strange mushrooms and torturing them for their amusement. Not only did the Snow Elves degenerate into something like [[TheTimeMachine Morlocks]], but what the Falmer went through fundamentally changed their very souls; theirs can be trapped in normal soul gems like any other beast, while sentient beings like humans or elves require black soul gems. The Dwemer literally devolved the Falmer into animals.
* A major part of the Reapers' modus operandi in the ''Franchise/MassEffect'' series. It begins with their Husk grunt troopers in the first game, which are augmented by variations and husks made from alien species in the others. But the crowning achievement is the revelation in the climax of the Suicide Mission that [[spoiler: Reapers are made by pasting up sapient species and implanting them in metallic superstructures -- and their next target is humanity]].
** The Collectors in ''VideoGame/MassEffect2'' [[spoiler: were originally Protheans the Reapers transformed into slaves]].
** In ''VideoGame/MassEffect3'' basically every major sentient race (save the quarians) gets their own monster version that they can be turned into. Add a couple of cross breeds for the charm.
* In ''VideoGame/LittleSamson'', Kikira the Dragon Lord, Gamm the Rock Lord and K.O. the mouse were all human once, but were transformed for various reasons. This is AllThereInTheManual and is nowhere brought up in the game.
* ''VideoGame/{{X-COM}}: Terror from the Deep'' has the Bio-Drones, whose [[MonsterCompendium UFOpedia]] entry reveals that they're actually made from living human brains that had been tortured to submission.
* The ultimate villain of the ''VideoGame/BatenKaitos'' games, [[spoiler: Wiseman]], is implied to have been [[spoiler: a human sorcerer who desired power so much that he abandoned his own humanity to obtain more.]]
* The [[spoiler: Faced Mechon]] in ''VideoGame/{{Xenoblade}}'' are eventually revealed to be [[spoiler: HumongousMecha piloted by [[HumansByAnyOtherName Homs]] put through UnwillingRoboticization.]] It's implied subtly early on by [[spoiler: minor antagonist Xord]], but it doesn't ''really'' hit until [[spoiler: [[WhamEpisode the party cuts open one... only to find Fiora, the protagonist's supposedly-dead childhood sweetheart inside.]]]] It also explains why [[spoiler: The Monado]] can't hurt them: [[spoiler: The Monado can't hurt Homs, and Faces ''are'' Homs.]]
* The remake of Non-Human for ''VideoGame/Action52Owns''. The titular creatures are horribly-mutated monstrosities, created when [[BigBad Dr. Murdon]] flooded a nearby village with mutagen.
* ''VideoGame/{{Fable}}'' and its sequels are heavy on this trope. Balverines are humans that got bitten, and hobbes are children whose souls were devoured by dark nymphs.
** FableTheLostChapters implies that [[spoiler: this is how Jack of Blades operates, as he possesses people through use of his mask until he finds another host body. His dragon form is his true form, however.]]
* Many of the creatures you encounter in VideoGame/FallenLondon were once men. [[spoiler: Then, in many cases, they made deals with the Masters of the Bazaar...]]
* ''VideoGame/DontStarve'' has Webber, who's HalfHumanHybrid of a spider. Since the spider tried to eat him while he was still a boy, it accidently merged with him.
[[/folder]]

[[folder:Webcomics]]
* The page image is from ''{{Nedroid}}'', "[[http://nedroid.com/2010/12/face-it/ Face It]]".
* ''Website/{{Bogleech}}'': [[http://www.bogleech.com/comics/comic18-trees.htm I was two men!]]
* Demons in DominicDeegan Were Once Men; we get to see some of the transitions. Most notable, of course, is [[spoiler:Siegfried]], whom we knew rather well before his death. ([[spoiler: In fact, he was the second recurring character to be introduced.]]) From [[http://www.dominic-deegan.com/view.php?date=2006-04-25 this]] to [[http://www.dominic-deegan.com/view.php?date=2010-09-16 this]] to [[http://www.dominic-deegan.com/view.php?date=2010-12-07 this]].
** Then there's Karnak, who is revealed to have been human near the end of the Ecstasy & Evil storyline, very casually by a former friend who has apparently given up even being sad about losing him. His back story is fleshed out as the comic progressed, and so far the only really bad thing he ever did in his ''life'' he repented halfway through and ran away to sacrifice himself heroically. May be the only being in hell not rightfully damned there.
*** Demon!Karnak, however, is both evil and a total JerkAss, although he ''has'' been having some character development. Had a Rorschach Moment in December 2010 and appointed himself ''Warden'' of Hell and informed the damned that they were all trapped in there with him.
*** Without becoming much less despicable, Karnak in the [[ComicBookTime last couple years]] has scaled the heights of CrazyAwesome. His [[GrievousHarmWithABody Siggy-flail]] was choice, as was his TheReasonYouSuckSpeech at his KangarooCourt trial. And then there's the simple things:
--->'''Karnak:''' [dramatic slaughter montage, final panel thought bubble] ''I hate this place.''
** A more typical progression of this is probably provided by Lady Loxo, who used to be soulbound to the Demon of Treachery back before Karnak exploded Hell into submission, and who becomes all serpentine and scaly after beginning to consume souls out of the 'feeding pits.' Bulgak Adrak is much more conflicted and his transformation doesn't progress nearly so smoothly, even once he gives in. Then he has an epiphany and [[StuffBlowingUp his soul explodes]].
** Then there's TIM, the eyeless, nameless infernomancer who provided the first evil in the comic and ''kept coming back'' with [[TookALevelInBadass new levels]] in BodyHorror.
** This trope is ''not'' applied to benevolent synthetic entities like [[{{Golem}} Quilt and Acibek]] who were made out of unwilling human victims. PoliticalCorrectnessGoneMad, possibly, but while the Acibek thing was tragic and the Quilt thing creepy, the focus is intentionally on who they themselves are, not their antecedents.
** Jacob Deegan, in his extremely long 'quest to become The Zombie Alive' phase, is explicitly trying for this effect as hard as he possibly can. The universal {{Squick}} is a ''perk''.
* Addressed in ''Webcomic/TheFancyAdventuresOfJackCannon''; as a combined punishment-and-strategy, Frankie is turned into a monster, shaped roughly like his old human self, but bigger, stronger, and uglier, with glowing red eyes. Gavin remarks that the eyes were a mistake; they made him ''too'' monstrous, making him easier for Jack and his family to deal with. Gavin restores his original human eyes so that the next time they make him fight someone, his opponents will be thrown off balance.
* ''Webcomic/ElGoonishShive'' has Aberrations. We've only met one on-screen, but he no longer looks human. [[BodyHorror At]] [[EldritchAbomination all]].
* ''Webcomic/YuGiOhCardGameGustoFanComic'': [[http://www.pixiv.net/member_illust.php?mode=manga&illust_id=26747520 Apparently, the Gishki fishmen were once members of the Ice Barrier, but were changed into their current forms using dark magic.]]
* Zhor from ''Webcomic/{{Drowtales}}'' [[spoiler:Ariel's father]] was once a Dark Elf, but was turned into a GiantSpider to save him from life threatening injuries. He's been like this for ''centuries''. As of Chapter 44, [[spoiler:the local MadScientist clan restored his original body. Zhor is confined to a wheelchair and has trouble speaking since he's not used to being a Dark Elf again after spending hundreds of years as a spider.]]
* The Overfiends in HeartCore were once humans and other mortal creatures [[MoralEventHorizon before they commited certain acts of evil]], turning them into powerful demons that were taken under [[BigBad Royce's]] wings.
* In ''VideoGame/AWitchsTale'', Aquell was once human, but Alice needed her power and turned her into a mermaid in exchange for Oceria helping in the war.
* The trolls from ''Webcomic/StandStillStaySilent'' used to be human. [[http://sssscomic.com/comic.php?page=158 Look carefully.]]
[[/folder]]

[[folder:Web Originals]]
* The Wiki/SCPFoundation's [[spoiler: [[http://scp-wiki.wikidot.com/scp-835 SCP-835]]]] (squick warning) as revealed in the uncensored report.
** Also [[spoiler: [[http://scp-wiki.wikidot.com/scp-811 SCP-811]]]].
** And if [[http://scp-wiki.wikidot.com/the-young-man this story]] is of any indication, [[spoiler: the HumanoidAbomination that is [[http://scp-wiki.wikidot.com/scp-106 SCP-106]]]].
* [[spoiler:All the monsters]] in ''Roleplay/RubyQuest''
* According to his song, [[WebAnimation/HomestarRunner Trogdor]] was originally a man, but then turned into a dragon-man before finally becoming a dragon completely.
** Then again, [[UnreliableNarrator the singer doesn't seem too sure about it.]]
* Web Serial Literature/{{Worm}} features Mannequin, once a meek GadgeteerGenius striving to avert the ReedRichardsIsUseless trope, now a member of the villain group called the Slaughterhouse Nine, encased in a special protective suit of armor that features retracting blades, unnatural ranges of movement, and detached limbs that he can swing, throw or fire from his suit using chains. Topping it off,[[spoiler: he may only be a brain and a few organs that fit in the armored torso]]. And he did it all to himself. The Endbringers might fit this trope as well.
* Pretty much all the minions of supervillain Dr. Macabre in the WhateleyUniverse. He kidnaps teens, transforms them into monsters, and forces them to do his bidding. The one captured by the police is a girl who is now mostly ghoul: she has a mouth full of needle-sharp teeth and requires human flesh to survive, despite everything she has tried.
* The ending of the second part of ''WebAnimation/BeeAndPuppycat'' might hint that [[spoiler:Puppycat [[AndThatLittleGirlWasMe was the cursed human in the fairy tale he told]]]].
[[/folder]]

[[folder:Western Animation]]
* The creepiest part of ''WesternAnimation/Ben10AlienForce'' is the revelation that the [=DNAliens=] were all once humans who had [[Literature/{{Animorphs}} brain slugs]] put on their heads. It's never really addressed after "Max Out", which was the [[DarkerAndEdgier most serious and darkest]] episode of the entire series, though.
** Except for one where an amnesiac man who can only recall being taken by the aliens turns out to be a disguised [=DNAlien=] and is restored to being a human again at the end of the episode.
* In one episode of ''WesternAnimation/InvaderZim'' ("Gameslave 2"), the rat people in the labyrinthine parking complex Dib gets lost in claim this happened to them, but Dib is unconvinced. A female one actually ''says'' "I was once a man," causing Dib to respond, bewildered, "But... you're a woman."
** Also, from "The Sad, Sad, Tale of [=ChickenFoot=]", we have this:
--->'''[=ChickenFoot=]''': I was once a man, like you! I once worked in a Chicky-Licky hut, like you!\\
'''Dib''': I don't work in a Chicky-Licky hut.\\
'''[=ChickenFoot=]''': DON'T LOOK AT ME!
*** For those not in the know, [=ChickenFoot=] is actually just some guy in a chicken suit, having problems with the zipper.
* Parodied in ''WesternAnimation/{{Sealab 2021}}'', in which a talking tree cobra claims "I was once... a man!" before saying "Just kidding, I've always been a snake."
* After Cobra Commander gets hit with altered fungus in ''WesternAnimation/GIJoeTheMovie'' and starts turning into a snake, all he can hiss is "I was once a man!" until the transformation is complete. Definitely the TropeNamer and what Sealab referenced in the above quote, despite not being "human" in the first place in this continuity.
** Although he got somewhat better in the series immediately following the movie with some assist, which justified in story the PowerArmor he wore.
* Windfang, Wrath-Amon's literal [[TheDragon Dragon]] from the animated series ''WesternAnimation/ConanTheAdventurer''. Once a famed general, he was taken prisoner during a battle in Stygia and transformed by Wrath-Amon. His wife-to-be ran from him in horror, leaving Windfang with nothing but 200+ years of servitude to the evil wizard. Wrath-Amon's second lieutenant Skulkar also was a human before a double whammy of sorcerous empowerment and necromantic curse turned him into and undead horror; unlike Windfang, though Skulkar definitely prefers being a monster (the episode with his backstory is also the one where he gets temporarily [[HumanityEnsues remade human]], which horrifies him).
** On the heroic side, Greywolf's brother and sister also were cursed into wolflike monsters under a villain's control (although fortunately by the end of the episode their curse was mitigated into them being intelligent free-willed wolves for most of the rest of the series). Also, in one episode where Conan gets sent to a BadFuture, we see what happens when Jezmine's [[HalfHumanHybrid serpentman heritage]] is brought to the fore; she later [[ScaledUp turns into a giant snake]] in a HeroicSacrifice to hold back Set so Conan can escape him - and then FridgeHorror hits you as to exactly ''why'' she would have that ability when she screams at Set as she "scales up" that [[GettingCrapPastTheRadar she'd never let him touch her again...]]
* ''WesternAnimation/GeneratorRex''. After the Nanite event, every living thing was infected by nanites. Many [=EVOs=] were human at one point. [[ParanoiaFuel And any one can go EVO at any time]]. And the only one who can cure them is a teenaged boy, and sometimes not even then.
* About half of the mutants in ''WesternAnimation/StreetSharks'', with the other half being sea creatures-turned-mutants. The good news is that the mutations pretty much can't change one's free will, so fewer humans are gradually transformed by the MadScientist.
** Not true...the bad guy's working on a formula to make them under his control. He just keeps having the test subjects escape...
* The BigBad, Skeleton King from ''WesternAnimation/SuperRobotMonkeyTeamHyperForceGo!'' was once a kind-hearted man called the Alchemist, who in fact was [[LukeIAmYourFather the one who created the monkey team]] to combat the monster he became. What makes his case really sad was that [[ViralTransformation his transformation wasn't by choice]].
* In an episode of ''WesternAnimation/{{Futurama}}'', Leela encounters an octopus-like creature in the sewers that claims (in a deep, growly voice) that it "used to be a little blonde girl named Virginia".
* In ''WesternAnimation/TeenageMutantNinjaTurtles2003'', the Turtles find an underground community of monsters who were once human, victims of the Foot Clan who were transformed into these creatures to mine valuable minerals. They get lucky, however; it takes many episodes, but Donatello is eventually able to find a permanent cure.
** Of course, since {{mutants}} are one of its main concepts, the trope appears in some way, shape or form in pretty much every iteration of [[Franchise/TeenageMutantNinjaTurtles the franchise]].
* In the ''WesternAnimation/AdventureTime'' episode "Holly Jolly Secrets", it's revealed that [[spoiler: the Ice King was a normal human man named Simon Petrikov until he bought an old crown and tried it on. He was driven insane by the visions the crown produced, heard voices telling him the secrets of ice and snow, and was physically changed into the frigid, blue-skinned Ice King. [[TearJerker The final moments of the video depicting his descent show his desperate plea to stop him from hurting anyone while he tries to overcome his growing insanity.]]]]
** In "Finn the Human", it's revealed that [[spoiler:the Lich was apparently a normal human who was mutated by the Mushroom Bomb's fallout into the undead OmnicidalManiac we all know and fear. In "Jake the Dog", the alternate universe ''Jake'' is transformed into the Lich instead.]]
* In an episode of the 1990s ''WesternAnimation/SilverSurfer'' animated series, the Surfer and a group of researchers come across an enormous green blob monster on a universal library planet built by {{Precursors}}. It's the precursors (and the crew of a pirate ship) themselves after they devolved into this form and linked up with each other in a hive mind of knowledge.
* PlayedForLaughs in the ''WesternAnimation/LooneyTunes'' short "Mutiny on the Bunny". A horrid-looking and clearly insane man runs down the gangplank from Yosemite "Shanghai" Sam's ship and has just enough time to turn to the audience and declare "I was a human being once!" before running off screaming into the night.
* Said by Walter Lankoswski (aka Sasquatch) in the 1996 animated Incredible Hulk TV series near the end, after choosing to exile himself from humanity after he's permanently transformed and injures a child while fighting the Hulk.
* ''WesternAnimation/SamuraiJack''; the title creature from "Jack and the Lava Monster" was once the king of a prosperous land until [[BigBad Aku]] attacked. Amused by the king's attempts to fight back, Aku imprisoned him in a stone for eternity. The king found a way to from the rock around him into a giant body (thus becoming the Lava Monster), and can only be freed and allowed to pass on to Valhalla if he is defeated in honorable combat by a mighty warrior.
* In ''WesternAnimation/StevenUniverse'', it's eventually revealed that [[spoiler: the gem monsters the main characters fight are actually corrupted Gems]].
[[/folder]]

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