[[quoteright:180: [[WesternAnimation/SuperRobotMonkeyTeamHyperforceGo http://static.tvtropes.org/pmwiki/pub/images/tvtropes62_6299.jpg]]]]
[[caption-width-right:180:"You were right, [[TheGadfly Sprx.]] It ''is'' me. ''I've'' got TheVirus!"]]

->''"At first, you'll be afraid. But don't worry. You're just becoming the monster you ''always'' were."''
-->-- '''Ada Wong''' to Derek Simmons, ''VideoGame/ResidentEvil6''

Characters who decide to [[JumpingOffTheSlipperySlope toboggan]] down [[TheDarkSide The Dark Slide]] will have a fun time of it... at first. It starts small, maybe an EvilMakeover with SpikesOfVillainy and RedRightHand. But there's a nasty surprise at the bottom of this insidious slide; those who commit especially heinous crimes, abandon all of their humanity for power, or allow their inner darkness to bloom into a blight won't just grow [[CuteLittleFangs tiny]] [[FangsAreEvil fangs]] or discover EvilMakesYouUgly, they'll find out [[TitleDrop Evil Makes You Monstrous.]]

This is usually a feature of legends, both in real life and in stories. Basically, a guy, gal or even animal becomes so mean, malicious, and generally '''''Evil''''' that they transcend their mortal existence and become a monster of legend. A scourge on man and beast. After killing enough, the SerialKiller goes from a man into a force of nature that [[HealingFactor just]]. [[ImplacableMan Won't]]. ''[[BackFromTheDead Die.]]'' The [[WickedWitch witch]] buried in the heart of the woods will rise from her grave and haunt it as a [[OurLichesAreDifferent half-dead corpse]] until her [[SoulJar spellbook is destroyed]]. The man who killed and ate his family out of hunger transforms into a {{Wendigo}}. The CreepyChild [[BullyingADragon everyone picks on]] lets the hatred fester and ferment until she becomes a living poltergeist. The devil worshipper so taints their souls that they [[DemonOfHumanOrigin transform into a demon]].

Then again, the (mostly) innocent might suffer this fate because of a {{Curse}} or TheVirus. In the most extreme cases the character will no longer be flesh and bone but MadeOfEvil. While it's unlikely the character wants to seek redemption, it's not impossible that a loved one from before the change can at least give them pause.

Can also be caused through ThePowerOfHate. See also/compare OneWingedAngel and ScaledUp. ThePunishment is related, but the transformation into a monster is forced by an outside faction. Contrast PowerUpgradingDeformation, where monstrousness makes you powerful. Compare with CuteIsEvil where cuteness is the warning.



[[folder:Anime & Manga]]
* The evil humans fought by the DWMA in ''Manga/SoulEater'' are often incredibly bizarre. In the anime it's stated to be because eating humans souls was turning them to Kishin, whereas in the manga only weapons can eat souls, leaving their strangeness more or less inexplicable.
* ''Manga/WolfGuyWolfenCrest'': When [[spoiler:Chiba]] is taken over by his bloodlust and obsession with killing Haguro, he becomes a [[NightmareFace deformed ogre]] instead of a werewolf.
* ''Manga/{{Berserk}}'' has the [[EldritchAbomination Apostles]], every one of whom WasOnceAMan (or woman, or child) before making their sacrifice to the Godhand and being reborn as demons, usually with a heaping helping of BodyHorror to go with their new superpowers. ZigZagged by [[spoiler:Griffith, who becomes slightly monstrous upon transforming into Femto, only to cross the BishonenLine and emerge even ''more'' beautiful after being reborn into the physical plane.]]
* [[spoiler:The Witches]] in ''Anime/PuellaMagiMadokaMagica'' are [[spoiler:former magical girls who have succumbed to the curses resulting from their wishes. While as magical girls they still look fully human, as witches they become bizarre monsters in a world of AlienGeometries]].

[[folder:Comic Books]]
* ComicBook/{{Wendigo}}, particularly the Creator/MarvelComics version. (Only 98% though -- the rabid man turns into Wendigo more or less permanently, not only on the anniversary.)
* In one issue of the [[ComicBook/TheLegendOfZelda Valiant Zelda comics]] Link steals the Triforce of Power from Ganon. As a result he [[PowerCorrupts starts turning evil]], and nearly completely transforms into a piglike monster similar to Ganon.
* In ''ComicBook/TheLeagueOfExtraordinaryGentlemen'', [[Literature/TheStrangeCaseOfDrJekyllAndMrHyde Dr. Jekyll]] indicates that Mr. Hyde has grown much larger from the exercise of sin.
* Marvel villain ComicBook/TheHood has a red hooded cape that gives him magic powers -- and is warping him into a demon.
* ''ComicBook/StarWarsLegacy'' Darth Krayt's own Vonduun Crab Armor(Yuuzhan Vong armor) has completely fused with his skin.
* Assuming that ComicBook/TheJoker started out as an ordinary man, whatever turned him into a Monster Clown certainly has this trope happen to him. However, in ''ComicBook/DeathOfTheFamily'', he has successfully outdone himself by first having his face removed, and then coming back one year later to wear it like a mask. Now he looks like a villain out of a SlasherMovie.
* ''ComicBook/JudgeDredd'': Dredd's nemesis Judge Death, a walking corpse who believes that life is a crime, was once a human being in an AlternateUniverse. Death spent his whole life killing people before allowing a pair of witches to turn him and his three lieutenants into undead abominations to achieve immortality. Since he was already pure evil long before his transformation, casting off the last of his humanity means the outside simply started to reflect the inside.
* ''ComicBook/NemesisTheWarlock'': After [[ANaziByAnyOtherName Torquemada]] was killed by Nemesis in a TeleporterAccident, he returned as a monstrous, distorted, clawed phantom who had to [[DemonicPossession possess rapidly-decaying hosts]] to interact with the physical world effectively.
* ''ComicBook/RequiemChevalierVampire'': A literal take, where people are turned into various monsters in the afterlife based on their sins in life:
** Religious fanatics become werewolves;
** Infanticidal women become harpies;
** Rapists become centaurs;
** Hypocrites become ghouls (female SkyPirates in this verse);
** {{Mad Scientist}}s become Archeologists, continuing their sick experiments and having to wear newly-flayed skins;
** Vampires are a more eclectic bunch, including Vlad Tepes, Attila the Hun, Alister Crowley, several Nazis, a Japanese participant in the Rape of Nanking, Maximilien Robespierre and Nero;
** People who committed evil in the name of empires (mostly British colonialists) become LizardFolk (led by the dragon KingArthur);
** Victims of evil either become zombies (seems mostly to apply to soldiers who fought in pointless wars) or lemures (ghosts that only move when their tormentor in life is expired on Résurection);
** [[spoiler:Hitler]] was somehow prevented from turning into anything, instead kept as a safety measure against the six million or so Lemures that passed on with his neck being snapped by Dracula.

* In ''Fanfic/ThousandShinji'' the main characters become worshippers of the ''TabletopGame/{{Warhammer 40000}}'' Chaos Gods. Their dark gods' gifts gradually mutate their bodies until Asuka becomes a red-skinned, bronze-haired, muscled demon, and Rei looks like a diseased, rotten living corpse.
* In ''Disney/TheBlackCauldron'' fic ''Fanfic/HopeForTheHeartless'', the [[OurLichesAreDifferent Horned King]] is revealed to [[WasOnceAMan have been a human]] who became what he is today centuries ago when he lost his [[AnatomyOfTheSoul heart and humanity]] with the numerous atrocities he committed in the name of [[EvilMentor his master Arawn]] and later in his own name after his master was vanquished.
-->'''The Horned King''': The heart is the messenger from the soul to the body, and keeps the two bound together as one. When the body fails, the heart ceases to be, and the soul is released from the body and sent elsewhere. You can see this in your elderly, however there is another scenario. After killing someone, the heart, the origin of all morality and emotion, begins to corrode. Slowly, but it is noticeable. [[SlowlySlippingIntoEvil The more one kills, the more difficult the damage is to reverse.]] After one has killed so much that the heart is gone and no longer holds the life in them, they begin to decay on the outside as well, as the heart binds the body and soul together, and without the heart, the soul cannot function properly. You see this with anyone who has killed before. They are alive, but they are not, and their outward appearance begins to reflect what they have become on the inside, and [[WalkingWasteland what they leave in their wake]]. I look like this because I am the embodiment of all that I have become. My heart turned to dust centuries ago, taking all life with it, and left me merely in a state of existence, my soul unable to work properly without it, thus my appearance.

* This is the nature of Jason Voorhees in the ''Franchise/FridayThe13th'' series. Notably, he started out as an [[ImplacableMan implacable]] but very human killer, until he morphed into an immortal undead killing machine over time.
* Freddy Krueger of ''Franchise/ANightmareOnElmStreet'' somehow managed to become an undead dream-dwelling human monster just by being ''really'' nasty to kids. The [[Film/FreddysDeadTheFinalNightmare sixth film]] reveals that he was given his powers upon dying by several nightmare demons.
* ''Franchise/{{Halloween}}'s'' Michael Myers went from a [[SuperStrength super-strong]], [[TheSociopath sociopathic]] human with plans to kill his sister to a [[JokerImmunity completely unkillable supernatural being]] hell-bent on massacring half of Haddonfield. And if you follow [[Film/HalloweenTheCurseOfMichaelMyers the sixth movie's]] canon, his power is making him grow bigger in each movie.
* In ''Film/{{Doom}}'', Chromosome 24 turns evil people (or people with a great potential for evil) into monsters and those who aren't into superhumans. [[spoiler:Sarge, who had earlier crossed a moral line but was still just following orders,]] starts out superhuman after being infected but turns into a monster during his fight with Reaper the moment it seems like he's really going to murder him.
* ''Franchise/StarWars'': Darth Vader got all his flesh burned off and earned a black skull-faced suit. Darth Sidious was disfigured into a withered wrinkled ghoul of a man. Darth Maul got tattoos all over his body. Only Count Dooku got away with his looks and stayed classy.
* Davy Jones from ''Franchise/PiratesOfTheCaribbean'' movies [[Film/PiratesOfTheCaribbeanDeadMansChest two]] and [[Film/PiratesOfTheCaribbeanAtWorldsEnd three]] was supposed to use his supernatural ship, the ''Flying Dutchman'', to transport the souls of the dead to the afterlife. After his lover [[PhysicalGod Calypso]] abandoned him, he in turn abandoned his duties and began instead to bargain for the souls of dying sailors to become part of his undead crew, at which point they would be tortured until becoming one with the ship. This caused him (and, by extension, them) to mutate into horrific amalgamations of human and sea creature.
* [[spoiler:Theodora]] turns into an ugly green hag in ''Film/OzTheGreatAndPowerful'' after [[spoiler:being tricked by her wicked sister Evanora (who is also an example) into eating a cursed apple]].
* According to ''Film/HanselAndGretelWitchHunters'', any woman who turns evil and becomes a witch cannot perfectly hide her rotting flesh to a thorough examiner. Hansel uses it to prove that Mina is not a witch [[spoiler:He turns out to be wrong, but the trope still applies because white witches like Mina are good and remain untarnished]]. Grand Black Witches can take on attractive forms, but when they use their powers they revert to their monstrous form.
* Chucky from the ''Film/ChildsPlay'' movies. The more time he spends in the Good Guy doll, the more evil the doll looks (as well as slowly mutating from plastic to actual flesh and blood).
* Ben Willis, the Fisherman from ''Film/IKnowWhatYouDidLastSummer'', was originally a revenge-driven killer who used a hook as his WeaponOfChoice. By the time of ''Film/IllAlwaysKnowWhatYouDidLastSummer'' he's apparently become an undead ghost/living memory still driven to kill.


[[folder:Folklore Mythology Religion]]
* The concept is more or less universal amongst human cultures -- literally regarding the inhumane as inhuman.
* This is one of the possible origins of a vampire, according to some accounts.
** And werewolves of the [[ImAHumanitarian cannibalistic]] SerialKiller type.
* This is also common in Myth/NativeAmericanMythology. Many, ''many'' monsters are spawned due to someone acting in such an anti-social fashion for so long that they become monsters.
** In the Native American mythology you may turn into a Wendigo if you become a cannibal.
* Myth/NorseMythology's Fafnir (who, depending on the source, is either a dwarf, a giant, or a man) murders his own father over a pile of gold, then turns into a dragon that constantly guards the treasure (''Literature/PoeticEdda'', ''Literature/ProseEdda'', ''Literature/TheSagaOfTheVolsungs''). While this appears to be a voluntary transformation, Fafnir never shifts out of his dragon shape.
* [[https://en.wikipedia.org/wiki/Shuten-doji Shuten-douji]] of Myth/JapaneseMythology, once an ordinary boy who callously burned up love letters and was cruel at heart. However, the smoke from this fire turned him into an [[http://en.wikipedia.org/wiki/Oni oni]].
* One of the reasons that God prevents us seeing demons is because they are ''so ugly and monstrous'', according to the Christian saints, who were able to see them, ''that they could drive us mad''.

* Eustace in ''Literature/TheChroniclesOfNarnia'', very allegorically becomes a dragon by being greedy and messing with a [[DragonHoard dragon's hoard]].
* Waraug the evil dragon in ''Literature/DealingWithDragons'' turns into a frog after displaying un-dragonlike behavior.
* This happened to [[BigBad Lord Voldemort]] from ''Literature/HarryPotter''. He lost his handsome looks and acquired ugly snake-like features after using too much [[BlackMagic Dark Magic]]. He also made himself very, very difficult to kill through the same means.
* Tends to happen to the most powerful Dead in the ''Literature/OldKingdom'' books. The deeper regions of death have strongly metamorphic properties, so that any spirit that forces its way back into the world of the living from there will have to be quite powerful to do so, but will no longer resemble its human form--and ''any'' dead spirit that willingly returns to life is a walking abomination against the natural order and a threat to any living person who encounters it.
* In Creator/EvaIbbotson's children's novel ''Dial A Ghost'', one of the ways OurGhostsAreDifferent is that evil ghosts decay in appearance over time while good ghosts still look mostly like they did in life. Some of it is apparently based on neglect for personal appearance and/or deliberate attempts to appear scary, but just plain being hateful seems to mess them up pretty well on its own--an unpleasant character seen just after his death is described as being even uglier as a ghost than he was as a man.
* Creator/JRRTolkien was fond of this trope, probably because of his own spiritual believes. Orcs, for example, are corrupted versions of Elves turned evil by Morgoth. Many Men serving Sauron eventually turn to be like this, like the MouthOfSauron. Gollum (originally a Hobbit) is another example of a normally good creature turn monstrous for the influence of evil.

[[folder:Live Action TV]]
* ''Series/BuffyTheVampireSlayer'':
** "[The Master] has grown past the curse of human features."
** Like the Master before him, Kakistos has grown past the curse of human features. Unlike the Master, he has cloven hooves in place of hands and feet.
* In ''Series/{{Supernatural}}'' Wendigo are created when humans dine on human flesh. The hunger grows and grows until they're nothing but beasts.
* In ''Series/KamenRiderDecade''[='s=] version of ''Series/KamenRiderHibiki'', an [[HenshinHero Oni]] who loses sight of [[ForGreatJustice justice]] and [[BloodKnight fights only to become stronger]] will become a powerful, corrupted, ox-like Makamou called Gyuuki. [[spoiler:This happens to Hibiki, forcing his young student Asumu to MercyKill him and take up the title of Hibiki.]]
** The line between monster and human is a common theme in Rider shows, since a lot of its heroes [[PhlebotinumRebel gained their powers from evil sources before using them for good]].
* ''Series/SamuraiSentaiShinkenger'', being heavily based on Myth/JapaneseMythology, has several bad guys who are explicitly ex-humans who went bad enough to become monsters. The villains for the show are even called Gedoushu, literally "Outside Path Ones", because they have left the path of humanity.

[[folder:Tabletop Games]]
* Fomori in ''TabletopGame/WerewolfTheApocalypse'' tend to be created when the Wyrm warps the flesh of those who are corrupt.
* Slashers in the ''TabletopGame/NewWorldOfDarkness'' are people who have done such evil things that the evil has warped them and given them special abilities to help them kill.
** In the same setting, the Mad are [[TabletopGame/MageTheAwakening mages]] who have committed so many heinous acts that their [[OurSoulsAreDifferent souls]] shatter, letting their magic start to leak out all over the place and manifest whatever psychoses pushed them over the edge.
** Similarly, the Centimani from ''TabletopGame/PrometheanTheCreated''. Usually driven over the DespairEventHorizon by the raft of crap Prometheans have to deal with, they turn their back on [[ToBecomeHuman the Pilgrimage]] and start dealing with [[TheDarkSide Flux]]. This usually results in mutations. ''Lots'' of mutations.
*** That would explain the name.
* In ''TabletopGame/{{Warhammer}}'' and ''TabletopGame/{{Warhammer 40000}}'', worshippers of Chaos will inevitably mutate--sometimes rather quickly--as the power of Chaos seeps into their being. Chaos mutations tend to be rather...grotesque, even horrifying. Eventually, this power will be the key to the apotheosis into a [[EldritchAbomination Daemon]] [[AscendedToAHigherPlaneOfexistence Prince]], although failure or inability to keep the power from overwhelming oneself, leads to succumbing to the mutations and becoming a mindless [[BodyHorror Chaos Spawn]], which is a much more common fate (provided they survived to that point).
** It's implied Doombreed, the oldest Daemon Prince of Khorne, was better known in life as Genghis Khan.
** The Dark Eldar of 40k, though they generally have a somewhat genteel evil look, have [[ScienceIsBad Haemonculi]], who enforce this trope ''on themselves'', with a combination of surgical and quasi-scientific means. One of them CameBackWrong from the dead, and every new death fails to restore him exactly to the previous state, so nowadays cheerfully lets himself be killed just so he can see what changed this time.
* ''TabletopGame/DungeonsAndDragons'',
** Aa lot of TheUndead work this way. Cannibals rise from the grave as [[OurGhoulsAreCreepier ghouls]], unrepentant murderers come back as wights, those consumed by hatred become wraiths or spectres, and so on. Liches are undead wizards who willingly become monsters in order to live forever.
** The ''Book of Vile Darkness'' has Feats for Evil characters (recommended only for [=NPCs=]) who voluntarily become monstrous (and hideous) to gain power. The Evil Brand and Willing Deformity feats are, in effect, self-inflicted BodyHorror to make the recipient CursedWithAwesome.
** There is also the taint mechanic introduced in the book "Hero's of Horror." In this you don't even have to do evil, mere exposure to evil can induce unpleasant effects.
** ''TabletopGame/{{Ravenloft}}'' invokes this to the point of having game mechanics for it. Whenever a player character commits an evil act, the DM makes a secret roll to find out if this attracts the attention of the [[PowersThatBe Dark Powers]]. This normally results in gaining a supernatural power and a RedRightHand to go with it. Repeated evil acts lead to further progression down a chart, and a PC who reaches this stage becomes a monstrous NPC Darklord. Some [[MoralEventHorizon "Acts of Ultimate Darkness"]] can automatically take a character to Darklord status.
* In ''TabletopGame/MagicTheGathering'' the planeswalker Ashiok is gradually transforming into something else as they orchestrate acts of evil. Thus far they've transformed about half their head into dark mist and a pair of slender black horns (in the process removing the eyes and brain, which they seem to have passed beyond a need for). Arranging the massacre of an entire city turned a few more specks of their cheek into this mist, indicating that countless atrocities lie behind the progress that's been made so far.

[[folder:Video Games]]
* In ''VideoGame/KingdomHearts I'', [[Disney/SleepingBeauty Maleficent]] embraces the Darkness and becomes a giant dragon as a result.
* As Sorceresses in ''VideoGame/FinalFantasyVIII'' grow older and continue to use their magic, their power begins to change their appearance into something less human and more monstrous. [[http://finalfantasy.wikia.com/wiki/Edea Edea]] was a fairly young sorceress so her appearance (while slightly altered) was still beautiful, whereas the older (and far crueler) sorceress [[http://finalfantasy.wikia.com/wiki/Adel Adel]] had morphed into a monstrous, muscular being. However, Sorceress [[http://finalfantasy.wikia.com/wiki/Ultimecia_%28Boss%29 Ultimecia's]] appearance is up for debate - her true form might be that of a [[EvilIsSexy sexy]], winged scantily-clad woman, or her true form might actually be her barely-human existence-sucking [[OneWingedAngel final]] [[http://finalfantasy.wikia.com/wiki/Ultimecia_%28Final_Boss%29 form]]. Considering how the other sorceresses look, the latter is more likely.
** Then there are the various sorceresses the player must fight during Time Compression. The [[http://finalfantasy.wikia.com/wiki/Sorceress_%281%29 first batch]] have odd skin colors and facial markings but still resemble beautiful women, the [[http://finalfantasy.wikia.com/wiki/Sorceress_%282%29 second batch]] look a little less human and have eerily [[EvilLaugh warped laughs]], while the [[http://finalfantasy.wikia.com/wiki/Sorceress_%283%29 final sorceress]] resembles a fat, bloated, purple slug.
* In ''VideoGame/FinalFantasyX'', this is how [[spoiler:one of Yevon's monks was turned into Omega Weapon]].
* ''Franchise/TheLegendOfZelda's'' Ganondorf, tapping into the full power of his Triforce of Power, transformed into the pig beast now known as Ganon. Although he is sometimes able to revert back to his human form at will, he definitely received the absolute refusal to actually stay down.
* In ''[[VideoGame/{{Diablo}} Diablo II]]'', the protagonist from the first opus, after defeating the eponymous Demon Lord, has put his soulgem on his own body in an attempt to contain his evil. As the game progress, Diablo takes over his body, gradually making him more monstrous until he turns back into the [[OneWingedAngel hideous]] [[EldritchAbomination Demon form]] Diablo used to assume.
* The further you go down the Dark Side in ''KnightsOfTheOldRepublic'', the uglier you get. When you're maxed out on [[KarmaMeter Dark points]], your eyes turn red and your skin gets ashen and veiny.
* In ''VideoGame/LiveALive'', this is the fate of [[spoiler:the knight Oersted]]. Originally one of the most straight up heroic player characters in the game, he [[FallenHero falls]] after he is betrayed and abandoned by everyone he knows. After accepting the mantle of "Demon King", he seems to prefer his new monstrous form to his original appearance. [[spoiler:He reverts to his original human appearance right before he [[DeathEqualsRedemption dies while warning the other heroes not to repeat his mistakes.]]]]
* [[{{VideoGame/TheElderScrollsVSkyrim}} Skyrim]] vampirism. A bite from a vampire will cause you to contract the disease that turns you into one but you have three days to cure it before you actually become one. So pretty much all vampires in Skyrim are vampires by choice.
** The fact that, in one quest, you meet vampires praying to Clavicus Vile to cure their vampirism, could be taken as indication that they were unwillingly turned into vampires. Or that they grew bored with it, who knows. Certainly vampirism is easy enough to cure before the three days have passed, a cure disease potion will do the trick, as will praying at a shrine.
*** GameplayAndStorySegregation. Just because the Aedra answer you, doesn't mean they answer everyone.
* Isamu in ''VideoGame/ShinMegamiTenseiIIINocturne''. He decides to seek the truth by himself, not accepting ''any'' help... and next time you see him, [[spoiler:he's absorbing countless stray spirits in the Amala Network to empower himself]]. Result? [[spoiler:He ends up with ''dozens'' of faces growing out of his body]].
* Ryu from the ''VideoGame/StreetFighter'' series has an evil form, cleverly named "Evil Ryu". In the series, it is said that those who train in the art of Ansatsuken (Ryu's fighting style), they can tap into even more power with Satsui no Hadou, which causes the user to do anything for victory, including murder. Ryu using this power is what gave series boss Sagat, a gaping scar across his chest for sequels to come.
** Also worthy to note, series TrueFinalBoss Akuma has been cursed with the power of the Satsui no Hadou, causing him to lose his mindset and his humility.
* ''[[{{VideoGame/OFF}} OFF]]'' plays this one straight with [[spoiler: [[VillainProtagonist The Batter.]]]] [[MindScrew May]][[RuleOfPerception be.]]
* In the ''Videogame/{{Fable}}'' series, your character's appearance is affected by your [[KarmaMeter moral standing]], with evil characters developing glowing eyes, pale skin and even horns.
* ''VideoGame/MetalGearSolidVThePhantomPain'': Due to the hidden "Demon Points" counter, every immoral action Snake commits (killing animals or enemy soldiers, attacking your buddies, killing Diamond Dogs staff, developing nukes, etc.) will slowly cause this to happen to him. At 20,000 points, his shrapnel horn grows significantly to resemble an actual horn, and at 50,000 points, it grows even longer and Snake [[BloodIsTheNewBlack becomes permanently covered in blood]], becoming a true demon.
* ''VideoGame/ResidentEvil6'': [[spoiler: Carla Radames]] infects Simmons with the C-Virus with this very trope in mind:
* In ''VideoGame/UntilDawn'', [[spoiler:true to Algonquian mythology, the act of [[ImAHumanitarian eating human flesh]] transforms a person into a monstrous {{Wendigo}}, an undead predator with lanky arms and vicious teeth. The mountain the protagonists have visited has been infested with them since 1952 when [[NoPartyLikeADonnerParty a bunch of miners resorted to cannibalism to survive after being trapped for weeks by a cave-in]]. The survivors were transported to a sanatorium where they transformed, massacred the nurses and other patients and fled into the night. Years later, when Hannah and Beth fell off a cliff resulting in the latter's death, the former's maiming and both being presumed dead, Hannah resorted to eating her sister's remains, transforming her into the fearsome Makkapitew.]]
* Arguably this happens in ''VideoGame/ShadowOfTheColossus'', as [[spoiler:killing the colossi gradually turns the protagonist into a monster.]]

[[folder:Web Comics]]
* Kavonn of ''Webcomic/CharbyTheVampirate'' curses [=LaBelle=] so that cruel actions on her part will physically alter her to be more "ugly", which eventually makes her a giant monstrous wolf.

[[folder:Web Original]]
* The hideous Creature, a supervillain in the ''Roleplay/GlobalGuardiansPBEMUniverse'' has been active as a super-criminal since the 1930s. Originally he was an officer in the SS and a spy for Nazi Germany when he found a mystic artifact called the "Stone Heart" that legend said would grant the one who possessed it great power and immortality. But it also transforms you so that your appearance reflects your "true self". Unselfish heroes who are kind, honorable, and generous tend to become tall, attractive, and strong in physically perfect bodies. Its safe to say that Creature was '''''not''''' kind, honorable, or generous...

[[folder:Western Animation]]
* Gibson from ''WesternAnimation/SuperRobotMonkeyTeamHyperforceGo'' when he's infected with TheVirus in the episode "Thingy".
* Though it's revealed in ''Luna Eclipsed'' of ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' that [[DarkIsNotEvil Princess Luna]] can change to her [[SuperpoweredEvilSide Nightmare Moon]] appearance whenever she wants, it was still her preferred and default form when she [[FaceHeelTurn turned evil]].
* ''WesternAnimation/BatmanBeyond'' has a couple examples that double as EvilMakesYouUgly:
** In his first appearance, the {{sociopath}}ic [[CorruptCorporateExecutive industrialist]] [[BigBad Derek Powers]] is revealed to have produced a deadly biochemical weapon to sell overseas. He ends up [[HoistByHisOwnPetard getting exposed to some of the poison gas himself]]. After receiving emergency radiation therapy, he turns into Blight, a [[ILoveNuclearPower radioactive]] supervillain who looks like a glowing green skeleton. Now his appearance really matches his inner self.
** This later happens to Charlie "Big Time" Bigelow; exposure to experimental agricultural chemicals turns him into a nine-foot-tall, deformed, hulking monster with SuperStrength. Which he doesn't mind in the least; he considers himself CursedWithAwesome, and likes the fact that people respect him now, even if it's because they're afraid of him. (In his second appearance, Max told Terry that "Charlie ''always'' was a monster, now he just looks the part.")
* ''WesternAnimation/TeenageMutantNinjaTurtles2012'': When Shredder mutates into the Super-Shredder in late Season 4, he turns into a freakish being with spikes, and his sanity continues to go downhill. He also abandons his affection for Karai in "Requiem" and leaves her to die in a burning building; on top of that, he has seemingly abandoned his love for Tang Shen, which was [[LoveMakesYouEvil his former driving motivation for going after Splinter]], declaring that it's fitting that Karai should die in the same manner as her mother. Both Karai and Splinter even lampshade it, declaring that Shredder is now a monster both inside ''and'' out.