[[quoteright:350:[[TabletopGame/MagicTheGathering http://static.tvtropes.org/pmwiki/pub/images/Transmutation2_3337.jpg]]]]
[[caption-width-right:350:[[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=2819 This]] [[HurricaneOfPuns fairy's tale just got very point-nant.]]]]

->''You saw the beauty side of me before! Now, with great pleasure, I introduce you to the BEAST!''
--> -- '''Zarbon''', ''Anime/DragonBallZ''

A Power Upgrading Deformation will make a character or creature much stronger but also make them look at the [[UncannyValley least]] [[WhatMeasureIsANonHuman inhuman]] and at the [[BodyHorror worst]] [[EldritchAbomination horrendous]]- and the process isn't likely to be [[PainfulTransformation pleasant]] or [[TransformationHorror pretty]] either.

Unlike the PsychoSerum where an ugly appearance can be a side effect, for the Power Upgrading Deformation the newly ugly appearance is the ''source'' of the enhancement: like sprouting CombatTentacles, pincers, [[GrowingMusclesSequence supermassive muscles]], MyBrainIsBig, [[TheGrotesque grotesque]] {{Cyb|org}}ernetics, etc. Because of this it would technically still be considered a MagicEnhancement or SuperSerum and not PsychoSerum.

If the setting has a BishonenLine, this drug, technology or spell will take the character to ''just'' before the return to prettiness (or if already there, start the cycle over). It's also worth noting that protagonists and main villains may get off easy with [[ButYourWingsAreBeautiful cool looking alterations]] that are [[OneWingedAngel way more]] [[SuperMode powerful]] while {{Mooks}} and secondary characters aren't so lucky.

The deformation may be a mix of: permanent (requiring a cure to remove) or temporary (granting a SuperMode), and perfectly stable (no more {{muta|nt}}tions) or continuously changing (risking falling to TheCorruption or PowerDegeneration). Because its effects are so nasty taking it tends to be treated as a GodzillaThreshold, with [[EmergencyTransformation only the direst of situations meriting it]]. Villains like the MadScientist and EvilutionaryBiologist will delight in kidnapping victims to use this on... usually paired with a MindControlDevice of course! [[note]](Can't have a PhlebotinumRebel, now can we?)[[/note]] On the other hand, some villains may [[ProfessorGuineaPig take it themselves]], become a OneWingedAngel and proclaim AGodAmI! Truly, EvilMakesYouMonstrous. Mind the ClippedWingAngel from overdosing.

Compare DangerousForbiddenTechnique, EvolutionPowerup, OneWingedAngel, HulkingOut, and TransformationOfThePossessed. See also BeautyToBeast and DeadlyUpgrade. Pretty much all {{Lovecraftian Superpower}}s result in this.


[[AC: Anime and Manga]]
* ''Manga/{{Berserk}}'':
** When [[EliteMook Zondark]] [[CurbStompBattle is unable to defeat]] [[AntiHero Guts]], [[AristocratsAreEvil the Count]] makes him [[OrificeInvasion swallow a part of him]]. This not only makes Zondark physically more powerful, but gives him the ability to grow CombatTentacles to replace lost limbs. The Count himself is one of the many [[OurDemonsAreDifferent Apostles]], [[DealWithTheDevil who have all been]] [[WasOnceAMan originally human]]. The Apostles can assume a human form but when they go OneWingedAngel [[BodyHorror "deformed"]] [[EldritchAbomination is an understatement]].
** Guts receives a set of magic armor, the Berserker Armor, that ups his already amazing combat abilities to the point where he seems almost untouchable, and even Apostles have difficulty fighting him. However, he's been warned that using it for too long will result in him losing his humanity. He's already begun to feel the effects: there's a SkunkStripe in his hair, and he's lost some of his sense of taste and colors are dulled in his vision. It's implied that the Skull Knight, an undead armored skeleton, was turned into what he is via many years of using the Berserker Armor.
* In ''Manga/{{Claymore}},'' this is how the titular SuperSoldiers are made, grafting in a piece of demon flesh to give them some of its powers, but they eventually succumb to TheCorruption, if they don't give in to their SuperpoweredEvilSide.
* The Tavoo/Taboo race in ''Manga/{{Psyren}}'' all have a core known as an Illuminus, which heightens their psionic abilities, but often disfigures them to the point of not even looking human anymore, usually taking on an [[EverythingsWorseWithBees insectoid]] appearance instead. The few exceptions are the high-ranking W.I.S.E. members, [[DoubleStandard and several others such as Tatsuo and Alfred.]]
* Similar to ''Claymore'' example, if the [[spoiler:Magical Girls]] of ''Anime/PuellaMagiMadokaMagica'' falls into DespairEventHorizon, they will turn into [[spoiler: [[EldritchAbomination Witches]]]]. This is actually a [[SubvertedTrope subversion]], since [[spoiler:Witches]] lose their sanity and acts purely on instinct, making them less effective in actual combat.
* The Zoanoids in ''{{Guyver}}'' are basically mutated humans whose new (revolting) forms are always tailored to give them a specific strength or super attack. [[MonsterLord Zoalords]] are however higher on the BishonenLine and look far less ugly than their underlings.
* Zarbon in ''Anime/DragonBallZ'' has a powerful second form, but it makes him look fat and ugly (whereas his normal form is a GorgeousGeorge type), so as a matter of vanity he avoids using it.
* ''Manga/{{Bleach}}'' gives us Ichigo's Hollowfication, as well as the Vizoreds who have similar powers. By tapping into their inner Hollow, they gain immense strength and speed, but have a bone-like demonic looking mask grafted onto their faces in the process. It is only temporary though. The mask can be broken off in battle, and it'll eventually crumble away in time. The mask's appearance varies from person to person, but all of them stop looking human.
* ''LightNovel/HighSchoolDXD'' has Issei after he sacrifices an arm to temporarily gain [[SuperMode Balance Breaker]]. This sacrifice is not actually losing the arm, its that whenever the energy in the arm builds up too much it begins to look like a dragon's rather than human.

* In TheNewUniverse in general and ''Comicbook/{{DP7}}'' in particular, [[MassEmpoweringEvent the White Event]] makes people suddenly have power-related mutations, many of which are like this. Moreso minor characters than the main ones, which [[CursedWithAwesome for all their complaints are really not that bad]].
* Creator/{{Marvel|Comics}}'s ''Comicbook/TheIncredibleHulk'', Dr Banner transforms into a giant green rage monster and has mega strength.
* In the {{New 52}} reboot of ''ComicBook/AnimalMan'', Buddy Baker now actually physically changes shape when he uses animal powers. The transformations are NOT pretty.
* The ''ComicBook/FantasticFour'''s The Thing is perhaps one of Creator/MarvelComics most iconic examples. After passing through a cloud of cosmic radiation he grew a [[SuperToughness super tough rock-like hide]] and SuperStrength to match. The downside is that unlike Reed, Sue and Johnny he ''can't'' turn his powers on and off, and is always the same huge frightening rock monster; an issue which has caused him no end of grief and in some continuities even suicide attempts.

[[AC:Fan Works]]
* In ''[[FanFic/SovereignGFCOrigins Origins]]'', a ''MassEffect''[=/=]''StarWars''[[spoiler:[=/=]''[=Borderlands=]''[=/=]''[=Halo=]'']] MassiveMultiplayerCrossover, this is discussed by an ex-Cerberus Phantom. The cybernetics process turns skin blue, leaves hardware sticking out, blood tends to seep out and cake in places, etc. In exchange, her weak biotics are massively enhanced (the Systems Alliance believed making such minimal talents military-grade to be excessively risky). Implied to apply to all Cerberus troops to some extent, as her engineer friend is just as ugly as she is.

* In ''Franchise/PiratesOfTheCaribbean'', Davy Jones and his crew are immortal, but have spent so long neglecting their job of {{Psychopomp}} for the dead at sea that they've become [[HalfHumanHybrid half-morphed into sea creatures.]]
* In the live action ''Film/StreetFighter'' movie, the project behind creating Blanca is basically an attempt at creating mutant {{Super Soldier}}s and brainwashing them.

[[AC: {{Literature}}]]
* In ''Literature/AMacabreMythOfAMothMan'', both the titular Moth-man and Ozzy were horrifically mutated (they both used to be normal guys), but also became much more powerful as a result.

* Just about every Chaos mutation in ''[[TabletopGame/{{Warhammer}} Warhammer Fantasy]]'' and ''TabletopGame/Warhammer40K'', since these mutations include things like CombatTentacles, pincers, extra mouths, cancerous growths...
** In 40K, most augmetics (metal replacement parts, ranging from bionic eyes to replacement arms to [[{{Spider-Man}} Doctor Octopus]]-[[SpiderLimbs style dendrites]]) are rather crude and ugly (ork versions are even worse). The Adeptus Mechanicus see the replacement of flesh with metal as the ultimate way to better themselves, so naturally they get [[UncannyValley the worst reactions]] from normal humans.
** Even becoming a Space Marine, the de facto "heroes" of the 40K universe, involves some pretty gruesome procedures, like the addition of extra organs, genetic modifications that lead to superhuman size and musculature, metallic/ceramic replacements for your skeleton, and an implanted "second skin" that interfaces with your PoweredArmor. Worse still, many of these upgrades are based on non-renewable implants that have to be harvested from dead Space Marines so they can be passed on to new recruits!
* Infernals in ''TabletopGame/{{Exalted}}'' have access to the Malfeas charms "By Rage Recast" and "Devil-Tyrant Avatar Shintai". When the Infernal's anima banner flares, Rage Recast means they manifest a selection of mutations from a library it grants them - because after the first couple of rounds you really want the guy running on radiation and crazy to gain an extra two feet of height and sprout batlike wings. The [[OneWingedAngel Shintai]] is even more extreme, manifesting the entire library at once - which, at high Essence, can provide a great many fangs, tentacles and horns.
* For a LighterAndSofter version, the Child of the Sun in ''TabletopGame/ChuubosMarvelousWishGrantingEngine'' can gain skills and minor powers by sprouting additional tendril-limbs. These powers tend to be based on the hopes and dreams of other player characters.

* In the fifth story line of ''Franchise/{{Bionicle}}'', the Toa Metru are captured and injected with [[TheCorruption Hordika venom]], which turns them into [[BeastMan half-animals]]. [[DownplayedTrope Downplayed]] in that while greatly increasing their physical strength, it also degrades their elemental abilities to some extent. The real downside however is they can't use any masks of power.

* The basis for Splicers in the first two ''Franchise/BioShock'' games. Specifically, they were users of a gene-modifying substance called ADAM- and along with the many cosmetic uses that it can be applied to, specially-prepared batches can give the user superpowers in the form of plasmids; unfortunately, abuse of the substance has resulted in addiction, disfiguration, and insanity. The main characters can also suffer a few of the tamer side-effects when they have plasmids equipped: [[PlayingWithFire Incinerate!]] clearly burns the wielder's hand; [[AnIcePerson Winter Blast]] causes icicles to grow through the user's flesh (complete with blood); finally, [[BeeBeeGun Insect Swarm]] results in a mixture of nasty-looking stings across the hand (in Jack's case) or a honeycomb forming out of the palm (in Delta's case).
* This comes up in ''VideoGame/DeusEx''; some cyborgs dislike the protagonist because they had to sacrifice their ability to look normal (thanks to the fairly obvious nature of their implants) while the protagonist's nanomachine based augments have barely any cosmetic effects (not to mention rendered them obsolete).
* [[EldritchAbomination Bydo]]-derived OrganicTechnology from ''VideoGame/{{R-Type}}'', under certain circumstances. For example, if the Claw Force is detached from the fighter too long, it temporarily mutates and goes on a rampage.
* In ''VideoGame/DigitalDevilSaga'', everyone infected by the demon virus has access to demon form, which is stronger than human form. Said demon form ranges from looking vaguely humanoid (most of the main characters), to slimes, to animalistic, to the [[EldritchAbomination worst looking of]] ''Franchise/ShinMegamiTensei'' [[EldritchAbomination demons]].
** In the main ''Franchise/ShinMegamiTensei'' series, human-demon fusion is quite likely to leave you like this, in ''IV'', some of the poor bastards who chose to become Demonoids were hit with ''Fusion Errors''. If you're not careful with Reds, in the same game, you will end up as a shambling undead. Or worse. Technically speaking, [[VideoGame/ShinMegamiTenseiIIINocturne the Demi-Fiend]] is also an example, as the parasite warped his body into that of a demon, even if he still closely resembles his human form, the horn he got was noted by WordOfGod to be a primitive sensory organ that grants him much of his demonic power, and the {{Power Tattoo}}s are actually lines of demonic lymph coursing through his body.
* Dr. N. Brio's appearances in the ''Franchise/CrashBandicoot'' series usually involve him drinking [[PsychoSerum mutagen]] and turning into a [[ComicBook/IncredibleHulk hulking green monster]] (though by the time of ''Crash: Mind Over Mutant'', it seems like he needs the mutagen to ''keep'' from transforming). [[spoiler:At the end of Mind Over Mutant, Dr. Cortex samples the mutagen himself, with similar results.]]
* ''VideoGame/TheBindingOfIsaac'' has this as the de jour - nearly half the permanent items upgrade Isaac at the cost of visually maiming him. For example, a coat hangar [[EyeScream goes straight through Isaac's eye socket to increase the firing rate of his tears.]]
* In ''Videogame/{{Borderlands 2}}'', one of [[TheBerserker Krieg's]] ultimate abilities is "Release the Beast", in which if he activates his action skill when at 1/3 of his health he transforms into a [[GiantMook Badass Psycho]]: His torso and right arm grow in size while his left arm shrivels up into a tiny stump. During this state his melee damage and damage resistance is massively increased.
* To some extent, evolution in ''{{Franchise/Pokemon}}'' is this - sure, that cute little Bulbasaur will get more powerful as a Venusaur, but it's not gonna be as cute if it becomes one.
* A number of human enemies from the ''Monster Girl Quest'' series experiment on themselves ([[AndIMustScream or]] [[FaceMonsterTurn on]] [[BrainwashedAndCrazy others]]) to gain the same attacking capabilities as monsters, by infusing their bodies with monster DNA to sprout CombatTentacles.

* ''WesternAnimation/{{Kaijudo}}'' has [[BigBad The Choten's]] evolution drug, which transforms the series' normally one-form {{Mons}} into a new, stronger form.
* ''WesternAnimation/StreetSharks'' has the gene splicing treatment that turns humans into sharks (and sea animals into monsters).
* Every ''Franchise/TeenageMutantNinjaTurtles'' cartoon had the mutagenic ooze which made them more human-like, while also mutating humans into uglier mutants.
* The splicers in ''WesternAnimation/BatmanBeyond'' used genetic engineering to become {{Half Human Hybrid}}s, which generally while animalistic weren't ugly. When their boss fights Terry, he takes a boat load of them and goes OneWingedAngel... until Terry gives him a ''second'' round of drugs which pushes him into ClippedWingAngel.

* The reason that steroids are so dangerous is the litany of side effects that comes with abusing them. Yes, steroids increase your muscles and your strength, but it comes with very bad acne, allergic reactions, discolored skin and infections. It also essentially makes you a ClippedWingAngel version of yourself, weakening the bones, ligaments and tendons in your body, which makes debilitating injury much more likely.