[[{{Bleach}} http://tvtropes.org/pmwiki/pub/images/cit_bleach_-_ichigo_hollow.jpg]]
--> ''"This is why I should be the one who's in control."''
->--''TalesOfSymphonia: Dawn of the New World''

-->''"Kill him now? Hmph, sorry Dad, he deserves to suffer a lot more."''
->-- '''[[TheMessiah Son Gohan]] enjoying Cell's pain upon reaching Super Saiyajin Level 2,''' ''DragonballZ''

A cross between UnstoppableRage and SplitPersonality. The fight's not going so well for our hero. He's wounded and at the end of his strength, and his barely scratched opponent (usually the AloofBigBrother) looks down at him and sneers.

And then the hero somehow suddenly taps into a massive hidden power source within him and unleashes a can of whupass on his opponent. (If the opponent is the AloofBigBrother, this may actually make him change his expression. Don't expect him to do more than widen his eyes, though).

It's not exactly the hero any more, though. He's got [[GlowingEyesOfDoom glowing eyes]], some new FacialMarkings, [[CreepyMonotone different way of talking,]] some [[EvilCostumeSwitch new threads]], and a lot less compunction about ripping someone to shreds. It's his SuperpoweredEvilSide. Think of it as the EnemyWithin when it's not the enemy, or as [[JekyllAndHyde Jekyll and super-Hyde]].

The SuperpoweredEvilSide may be a distinct alter ego - a literal "inner demon" - or merely the 'Berserker mode' of the character. Either way, it's capable of doing massive amounts of damage before the hero returns to normal. Keep in mind, [[SplitPersonalityTakeover the threat of the hero]] [[FreakOut not returning to normal]] is always there. You're usually safe until you start thinking EvilFeelsGood.

The narrative purpose of having a super-powered evil side is that it provides a way of saving a hero who is otherwise beaten, but without making the hero look disproportionately powerful. It answers the question "why don't they just do that all the time?" with "because then the evil would take over." Additionally, if it leads to a FaceHeelTurn, it can serve the same purpose as GoodIsDumb in reverse -- it justifies taking one member of the FiveManBand or whatever, and making them a match for their entire team while they've given in to evil.

The converse of WithGreatPowerComesGreatInsanity, since in this case, [[PowerBornOfMadness with great insanity comes great power]].

In conclusion, Evil is stronger just as EvilIsCool... and gets [[TheDarkSide cooler and stronger the more you use it]].

One possible variation on this trope makes the Evil Side the ''original'' personality. This creates the odd situation of an "Evil" super-powerful monster whose "Good" not-as-powerful personality is dominant for whatever reason.

This can sometimes cross over with BewareTheNiceOnes and can get into NightmareFuel territory. Compare with CrouchingMoronHiddenBadass and OneWingedAngel. Contrast HeroicResolve, MyNameIsInigoMontoya. May be caused by TheCorruption. One possible way of [[TookALevelInBadass Taking A Level In Badass]].

SubTrope of EnemyWithin.

----
!!Examples:

[[foldercontrol]]

[[folder:{{Anime}} and {{Manga}}]]
* Himura Kenshin from ''RurouniKenshin'' is a technical pacifist in battle, fights with a reverse-blade sword and vowed years ago to never kill again. But if things seem to be getting out of hand even for him to handle (usually when his friends are in danger), his fighting style and mindset slowly begin changing into the highly pragmatic and ruthless Battosai, the assassin he was ten years ago. He switches the extremely humble ''sessha'' for the brash ''ore'', loses the ''de gozaru'' from his speech, his eyes turn gold and more slanted and he moves for the kill. In the anime, Battosai seems to be considered an actual personality Kenshin has learned to seal off by creating his rurouni persona - he has to literally punch himself in the face to push it back and revert back. In the manga, this gets lampshaded a bit when Kenshin remarks that his face muscles have cramped and he isn't able to end his permanent death glare.
* Son Gohan of ''DragonballZ'' during the Cell Games is easily the most chilling example in anime. It is more than a little disquieting to watch the kind-hearted and sensitive little boy we have come to care about turn into a gleefully cold-blooded sadist when he achieves the Messianic power of Super Saiyajin 2.
** The original Super Saiyajin mode was originally intended to be a SuperpoweredEvilSide, as when Son Goku is in this state, he cannot use the SpiritBomb, which requires a pure heart to use, because the Super Saiyajin state fills his heart with rage.
** Vegeta seems to regain some of his old nastiness whenever he fights as a Super Saiyajin (against the androids first, then later against second-stage Cell). Even Son Goku loses his usually unbreakable self-control the first time he achieves Super Saiyajin while fighting Freeza, though he seems to partially regain it by the end of the battle.
** In addition to the above, it should be noted that when Son Goku and Son Gohan transform into Oozaru, they also become mindless beasts, while increasing massively in power. This has been used both to save Son Goku from the clutches of the Emperor Pilaf, and allowed Son Gohan to beat Vegeta after crushing him from having his tail cut off and losing the transformation.
* Ichigo in ''{{Bleach}}'' is the embodiment of this trope. He becomes much stronger when his inner hollow is allowed to come out, or comes out on its own accord. The inner hollow is a completely different personality, behaving differently and mocking Ichigo about his weakness even as he attacks their common enemy. Ichigo gains half a hollow mask, yellow eyes (the picture in the main article) and the ability to block sword strikes with his bare hands. His sword's energy blasts become [[strike:red]] black (specifically stated in the manga) and can be guided to the target. Sure enough, the first time he uses this form in combat is during his final battle with Byakuya Kuchiki, an AloofOlderBrother, in the Soul Society arc. Sure enough, Byakuya doesn't do much more than widen his eyes a bit.
** The best part about this form is that it is truly opposite: he is always [[SlasherSmile smiling]], as opposed to Ichigo who is (almost) always frowning, he tells jokes, he's the complete opposite of Ichigo.
** Later on, Ichigo [[spoiler:gains the ability to control his hollow through the help of the vizard, enabling him to voluntarily call forth a full mask and consequent powers. However, at the start, he can only maintain this form for 11 seconds. By the time the Huecho Mundo arc rolls around, the mask has become just another power-up, its 'evil' being utterly gone and leaving Ichigo in control.]] This wasn't achieved without a climactic BattleInTheCenterOfTheMind, however. Twice, even.
*** And judging from the last chapters, [[spoiler:his SuperPoweredEvilSide TookALevelInBadass, complete with evidence of further SanitySlippage. Instead of a cackling lunatic in a mask, he becomes a full hollow that speaks only in roars and likes taking his opponents apart one dismembered limb at a time.]]
* Inu-Yasha's demon side in ''InuYasha'', although it could also be interpreted as WithGreatPowerComesGreatInsanity, as his bouts of insanity stem from having too much demonic power for his half-human body to handle. The Tetsusaiga acts as a RestrainingBolt.
** Subverted in that eventually the Tetsusaiga itself is so powerful that his demon side is actually [[PowerupLetdown weaker]] by comparison.
** Suikotsu of the Shichinintai is a [[TheMedic doctor]] with SplitPersonality whose darker side is a sadistic, blood-thirsty murderer.
* In ''{{Naruto}}'', the Kyuubi, Sasuke's cursed seal, and to a lesser extent Shuukaku are all Superpowered Evil Sides, even though all three can be suppressed in some way.
** Sasuke's case actually only happens during the first activation. Additionally, the source of the cursed seal and its original user, Jugo, is an odd case but still fits to the point that he's called "Jugo of the Scales" (or "Bipolar Jugo" depending on the translation). The "odd case" comment comes from the fact that despite the SuperpoweredEvilSide being ''caused'' by the cursed seal, it's triggered independently of its use. This means he also fits to some extent in SplitPersonality and that actually using the cursed seal doesn't increase the chances of snapping and becoming a killing machine, so he can use it's power without much ''additional'' worry ("additional" being a key word here as he's ''always'' ready to snap). In theory he should be able to remain in his normal form while crazy, but since he wants to kill everyone this hasn't happened as of now.
* Alucard of ''{{Hellsing}}'' is a sadistic, mass-murdering, cannabalistic vampire with a low opinion of human life as a general thing. If you actually manage to get him on the ropes, though, he can transform into a ShapeShifting [[CosmicHorror black horror]] that can butcher opponents en masse or [[spoiler:release all the souls he's eaten as a gruesome, blood-soaked army.]]
** However, there's no real indication that he loses control or anything when he does that. That's just his superpowered [[OneWingedAngel side...]] he's already got the evil covered. Arguably, Alucard himself serves the same purpose as a SuperpoweredEvilSide for the Hellsing organization as a whole.
** Seras Victoria's berserker mode could be counted as her SuperPoweredEvilSide.
* Lucy from ''ElfenLied'' is a variant of this trope - while she was originally the 'true' personality, she suffered a nasty head wound that caused SplitPersonality and left her nonpowered good side, CuteMute Nyuu, in control. The times when her 'true' self resurfaces fits this trope to a tee.
* Orson from ''RecordOfLodossWar'' is literally a Berserker Class and, when he gets angry, he becomes an unstoppable killing machine that wields a massive claymore as if it were a toothpick.
* The "Shiki Nanaya" within Shiki Tohno in ''{{Tsukihime}}''. Crucial in the manga/game but only used once (and not explained) in [[AdaptationDecay the anime]].
** Many other characters in the {{Nasuverse}} have an 'inversion impulse,' the desire to go psycho and unleash their bitchin' superpowers on the world in an orgy of murder. Being a true ancestor or successor to a demonic or psychic bloodline helps. Sometimes, such as in Shiki Ryougi's case, this a true split personality, in others it's just buried bloodlust or some less conventional psychological artifact. In Arcueid's case, being a True Ancestor means using most of her insane amount of power simply repressing this impulse; letting loose would [[UnstoppableRage increase her power orders of magnitude.]]
** ''MeltyBlood'', the fighting game based on ''{{Tsukihime}}'' and ''Kagetsu Tohya'', uses the BigBad's plot-device-like powers to summon the SuperpoweredEvilSide of several characters, which leads to interesting pre-fight exchanges in "{{Doppelganger}}" fights.
** In Kagetsu Tohya it's revealed that his super powered demon killing side terrifies him. As such, he actually appears to have stopped using it.
* Sumire's Anti-Virus mode (called "Berserker") in ''VenusVersusVirus''.
* Vash the Stampede's eponymous weapon in ''{{Trigun}}'' is triggered involuntarily by such events.
* Yugi's powerful alter ego in ''{{Yu-Gi-Oh}}'', Yami Yugi, is not actually evil, but he is a lot less concerned for the well-being of his enemies. Yami Bakura and Yami Marik, on the other hand, are both gleefully, psychotically evil. (Regular Marik isn't exactly a nice guy either.) In the manga, however, Yami IS evil, at least initially.
-->'''Yami Yugi:''' Couldn't I just mind-crush him?
-->'''Yugi:''' You can't fix all your problems by mind-crushing people.
-->'''Yami Yugi:''' Oh, come on! Just one little mind-crush, it'll barely hurt him.
-->'''Yugi:''' No! Bad pharaoh! No mind-crush!
-->''YuGiOhTheAbridgedSeries''
** WordOfGod stated in a Shonen Jump Q&A that Yami Yugi actually WAS evil at first, due to a few millennia of his soul being imprisoned, but that his experiences with Yugi and his friends gradually helped him regain his sense of righteousness. This plot point was mostly, if not entirely, removed in the second animated adaptation.
*** Funnily enough, the plot point was revisited in the otherwise fairly pointless "Waking the Dragons" arc. After Yugi's soul gets imprisoned, leaving Yami in control 24/7, he starts to regress back to his original evil nature, without Yugi's kind nature there to temper his drive for vengeance. Which makes him a more vulnerable target to Dartz's machinations.
*** Not entirely removed. This is played with in the Yugi vs. Kaiba rematch when Yami Yugi is going to attack but the shockwave might have caused Kaiba to fall off the ledge. Yugi is appalled that his alter ego would have attacked and "was willing to go all the way against Kaiba," leading to a HBSOD
** Judai, Fubuki, and Kaiser in ''{{Yu-Gi-Oh GX}}''... except Kaiser doesn't gain an evil side as much a [[FreakOut new evil persona]].
** Displayed in ''{{Yu-Gi-Oh 5Ds}}'' with the Dark Signers. Aki, too.
* Tequila in ''GalaxyAngel II'' (and ''Galaxy Angel Rune'', but since when has the anime had any actual battles?)
** Tequila isn't really evil, though. Just completely uninhibited.
* The eponymous warriors of ''{{Claymore}}'' constantly run the risk of becoming "Awakened Ones" when using their powers. In that state, they become their superpowered evil sides without any chance of turning back to their original forms.
** The twist is [[spoiler:HeroicWillpower lets the sufficiently motivated come back from the brink and even retain some control after completely transforming]].
* Quiet and retiring Haru's alter ego, "Black Haru," from ''FruitsBasket'' is a humorous take on the trope. In the anime (or early in the manga), at least. It's played for some serious drama later in the manga.
** Along the same vein, that goes for the brief 'cameo' of [[spoiler:"Black Yuki"]] in the later chapters as well.
* When Yuri from ''KyoKaraMaoh'' reaches an appropriate level of moral outrage, he involuntarily transforms into a larger version of himself with cooler hair, amazing magical powers and a thirst for justice.
* When Kazuma of ''KazeNoStigma'' taps into his evil side (really a reversion to his old behavior in his backstory), he will do whatever it takes to accomplish his goals, no matter who he has to hurt (or mind crush!). [[spoiler:Kazuma may actually be a subversion if Ayano is correct in her analysis when she faces him to try and stop him from going on his rampage. She states quite clearly that he used to be so overwhelming that it seemed to be stupid to be afraid of him. Because she was afraid, it was proof that he was weaker than before. In any case, he's still very kick ass.]]
* In ''JojosBizarreAdventure part 5'', the protagonist Giorno Giovanna develops a new stand "Golden Experience Requiem" which is intelligent and can act on its own, and completely destroys his enemy Diavolo, causing him to experience death over and over again for all eternity.
* Ginji's Raitei persona in ''GetBackers''. [[spoiler:Kazuki]] also has one, when [[spoiler:he releases the seal on his Stigma eye.]] The same way Ginji is the "Thunder Emperor," he's "the Prince of Terror."
* In ''Daa! Daa! Daa!'', you can see a crystal-clear example in Christine, the older Hanakomachi... when a girl (human, alien, it doesn't matter) approaches his beloved Kanata in a remotely romantic way, she emits a black aura and her eyes glow: it's your cue to get the hell away. In such state she is capable of feats like lifting trees & breaking concrete walls. She's not evil, just [[ClingyJealousGirl clingy]].
* Subverted in ''SamuraiDeeperKyo'': prior to his [[TimeToUnlockMoreTruePotential further training]] under his master Muramasa, Onime no Kyo was in fact ''weaker'' than Mibu Kyoshiro, who was merely [[ObfuscatingStupidity feigning weakness]] to complete the facade of a harmless medicine peddler.
* Moka's "super-vampire" side in ''RosarioToVampire''. Super-Vampire Moka speaks to her normal self through her Power Limiter, giving her guidance that she needs. This one isn't evil so much as very emotionally cold, though.
* In ''Heroic Age'', the giant mech-like warriors of the Heroic Tribe, called the Nodos, can eventually let out a Superpowered Evil Side when two fight together - whether against each other, or side by side - called Mental Chaos, when they enter a pure blind berserker rage. Considering a single Nodos can sometimes destroy a whole planet on its own at its normal levels of power, a Nodos in Mental Chaos is a frightening thing indeed. In Bellcross, the Nodos that serves the human Age, Mental Chaos is shown by his skin and "armor" turning dark gray, almost black, and a set of blue spheres implanted in his body begins to glow bright red. And he roars a lot.
* Guts, the protagonist of ''{{Berserk}}'', is known to slip into this state during particularly tense moments.
** [[spoiler:In the manga, this becomes personified by The Beast, a feral lupine creature formed from the considerable amount of rage at the Godhand (and Griffith in particular) and other negative emotions that Guts suffers from after the Eclipse. When Guts is under The Beast's influence, he becomes a danger to everyone around him, even the people he loves -- at one point in the manga, [[NearRapeExperience he almost rapes Casca while under its influence.]] Later on, he acquires the Berserker Armor, an extremely dangerous cursed Dwarven artifact that blinds its user to pain and limitations and causes them to see everything as a threat. It also becomes a kind of physical conduit for The Beast.]]
* In the h-anime ''Makai Tenshi Jibril'' (Translated title: ''Jiburiru - The Devil Angel''), {{Meganekko}}-with-a-crush Meimi is given the sadistic MagicalGirl persona of Misty May, the "Devil" counterpart to the heroine Rika, (St. Jibril/Jiburiru)
** Closer to the trope definition would be Rika's evil form in the sequel, or Hikari's Black Aries form in the third game.
* This happened in ''{{Guyver}}'' once, but it was a doozy. [[spoiler:After his father was turned into an Enzyme Zoanoid and ripped out Sho's brain, the Guyver itself took over Sho and killed his father. Let's just say that when he found out, he didn't take it well.]]
** Though this wasn't so much the Guyver being evil, as obeying its Prime Directive of wearer-preservation.
* In ''DGrayMan'', Allen's [[EmpathicWeapon Innocence]] seems to have a mind of its own and tends to upgrade itself when Allen gets particularly angry or emotional. It also can control Allen when he's unconscious, and it tends to be very vicious. Then again, it's only dangerous to [[TheHeartless Akuma]].
** Also the vampiric Arystar Krory, although he has less of a SuperpoweredEvilSide than a Superpowered DeadpanSnarker BadAss Side.
** There's also the Noah, although they're [[AffablyEvil (affably) evil]] to begin with.
* How has Son Goku from ''{{Saiyuki}}'' gone unmentioned? His 'evil side', the Seiten Taisei, is akin to a heretical chaos god and nearly overthrew the Heavens, goes on an UnstoppableRage whenever unleashed, and usually ends up trashing both the enemy, AND his teammates by the time he's finally stopped. The only thing that keeps him in check is the crown he wears which serves as a RestrainingBolt.
* In ''SoulEater'', [[spoiler:Soul Eater]] is infected by some of Medusa's black blood, which manifests itself as a devil living inside his head [[DealWithTheDevil offering him power in return for giving in to the insanity]]. On the one occasion [[spoiler:he and Maka]] give into it in order to stand a chance against TheDragon, the trope is almost fulfilled to a tee... Except it's not so much a 'superpowered evil side' as a 'NighInvulnerable giggling lunatic side who catches TheDragon completely off-guard'. [[spoiler:They ''barely'' make it back to sanity, which the devil seems to consider this a temporary setback.]]
** While not anywhere as drastic a change as Maka, Stein's tactic against Medusa, of giving into his own madness, could also be seen as this. Though this side is not so much 'hidden' as it is what Stein would ''be'' if he didn't hold himself back through fear. He also seems able to control it frighteningly well, if Spirit's comments at the time are anything to go by.
* Koyori in ''NurseWitchKomugi'' has a literal evil MagicalGirl SplitPersonality that she is completely unaware of.
* Lina from ''{{Slayers}}'' when she's [[spoiler:possessed by the being that accidentally created the universe and would really like to undo it.]]
** IIRC, WordOfGod says that [[spoiler:The Lord of Nightmares less an evil entity and more a CosmicHorror whose motivations are so alien that her moral character is essentially irrelevant.]]
* The "berserker spirits" aka The Dragons from ''IkkiTousen''. So far, we have four dragon holders: Hakufu, Ryuubi, Sousou, and [[spoiler:Ryoumou]]
* ''SonicX'': Absorbing the negative energy of an entire factory's worth of fake Chaos Emeralds coupled with seeing his friends tortured unleashed [[http://uk.youtube.com/watch?v=XtvplkXKSaY Dark Sonic]] for the first time in animated continuity. Complete with white eyes and navy-dark energy all over his body, plus the ability to tear anything that pisses him off to shreds.
** Super Sonic in the British ''SonictheComic'' comic series. In that comic's canon, the Chaos Emeralds are full of pure evil (as energy), rather than their neutral alignment as confirmed as canon by ''Sonic Adventure''. Super Sonic came about by overexposure to the Chaos Emeralds, and as such... he's totally insane, and totally evil. Not to mention sadistic, psychopathic... and equipped with the power of the Chaos Emeralds.
** Although it's not strictly ''evil'', the Were-Hog form in ''SonicUnleashed'' could be considered a Superpowered Evil Side... except that Sonic isn't really evil in that form, just super aggressive and destructive.
*** This exeption is {{Lampshaded}} after it is revealed that [[spoiler: Chip is actually Light Gaia, a benevolent spirit, who is guarding the earth.]] Sonic then asks, if it could be Chip who keeps him from succumbing to Dark Gaia and becoming evil when in Werehof-Form, to which Chip replies that he has nothing to do with him, it's Sonic's kind heart alone which lets him keep his sanity.
* The main character of ''666 Satan'' is actually the container of Satan himself along with nine other demons that have the ability to possess people. There are also ten angels, none of which are evil or attempting to take over but some are incredibly vain and judgemental.
* While not necessarily "evil," a mechanical version of this can be found within ''GundamWing'', specifically in the form of the Zero System, a computer system in the Wing Zero which interfaces with the pilot's brain, enhancing his reaction time and aggressiveness, and allowing him to process tactical data with superhuman speed and efficiency... with a fun little side effect of driving the pilot temporarily insane. The Epyon uses a knock-off of the Zero System which has an even worse effect; when Heero pilots that mecha temporarily, he goes on a murderous rampage.
** ''{{Gundam 00}}'' also has fun with this - Allelujah Haptism has a SplitPersonality: Hallelujiah, a blood-thirsty "warrior" half whom is much more skilled than just about any other pilot in Celestial Being, Setsuna included.
*** Then subverted with [[spoiler:The "Ultimate Soldier", aka H/Allelujah or Doublelujah, whose an even ''better'' pilot and integrates the best parts of both personalities, including Allelujah's morals.]]
* Dark Schneider/Lucien in ''{{Bastard}}''. Tiny, fifteen year old boy turns into the infamous eponymous bastard, the all-powerful Exploding Wizard. Then subverted since Darsh does a lot of dorky things outside of battle and seems much more like a JerkWithAHeartOfGold than anything else, with some people often remarking that compared to the Dark Schneider of fifteen years ago, this one is practically a ''saint''.
* In ''{{Saikano}}'', Chise's personality while in [[PersonofMassDestruction the Ultimate Weapon form]] could be psychotically vindictive, threatening on multiple occasions to utterly eradicate anyone who got in her way or made her mad, be it friend or foe... and that she could do so with ridiculous ease made her even more horrifying.
* Parodied in ''YuYuHakusho''. Yusuke [[spoiler:dies, it is revealed that he is in fact part demon. Said demon blood kicks in and he [[IGotBetter gets better]], with his demonic powers lending him a considerable increase in strength.]] He then decides to have a little fun at the expense of some alarmist commandos who wanted to take him out.
-->'''Yusuke:''' For what I desire is ending the world and everyone in it. For I am [[spoiler:the mighty Mazoku, Lord of Evil! And now, after hibernating for a thousand years I will finally reveal my true form!]] AHAHAHAHAHAHAHAHAHA... psych!! Damn, you guys are gullible!.
** Late in his fight with Sensui, [[spoiler:the trope is played straight, as while he still isn't quite able to overpower him, his demonic ancestor Raizen takes control of his body and makes him considerably faster and more powerful, enabling him to easily defeat Sensui]].
** Sensui himself is an inversion of this trope. Of [[spoiler:his seven personalities, the strongest one is Minoru, the original one, and the only one to remain pure and innocent.]]
**Kurama displays a variant on this trope in the Dark Tournament when [[spoiler: his opponent tries to reverse his aging to make him a baby, but goes to far and reverts him to his previous incarnation as a powerful demon bandit.]]
* Mayo Kagura from ''{{Mai-HiME}} Destiny''. In a series where everyone has psychic powers, it's hard to stand out when you have boring ol' telekinesis... unless you have a SuperpoweredEvilSide that can ''uproot trees and use them as weapons''.
* Ryo Takatsuki from ''{{Project ARMS}}''. His [[RedRightHand right arm]] is a nanite-based entity known as the Jabberwock. Get him ticked off enough, and the Jabberwock spreads over and takes control of his entire body. Though more really, really angry rather than outright evil, this doesn't stop Jabberwock from doing such feats as [[spoiler:tearing apart an entire helicopter division, numerous other ARMS, emitting ''fire'', and much, much more. Oh yeah, and it evolves too.]]
* In ''OmamoriHimari'', [[spoiler:all demons, including Himari, can fall prey to their instincts or desires and become savage beasts. In Himari's case, she turns into a nigh unstoppable juggernaut-but, like any other demon, she runs the risk of not being able to return to normal.]] It's explicitly stated that in this situation, they ''will'' be exterminated.
* As of recent events in ''MahouSenseiNegima'', it seems that [[spoiler:the "Encroachment of [[BlackMagic Magia Erebea]]" is causing Negi to develop one of these.]]
* Urd of ''AhMyGoddess'' (at least in the anime).
* [[{{Pokemon}} Pikachu}} in the [[Anime/Ptitlei015gc004kw4 Anime]] practically turned into a demon when he was [[spoiler:possesed by Groudon.]]
[[/folder]]

[[folder:{{Comic Books}}]]
* Though not portrayed this way in the original comics, all subsequent portrayals of the Venom symbiote from ''Comicbook/SpiderMan'' have made it out to be this, with even the comic book symbiote having been {{RetCon}}ned into a more malevolent entity.
* The Comicbook/IncredibleHulk is the canonical super-Hyde. The Hulk, over time, has been softened down from "evil" to "pure id". Not that that stops him from racking up the damage bill every time he shows up.
** Banner does have the Devil Hulk personality inside him, which is pure evil.
** As well like [[JerkAss Gray Hulk]] and [[WhatHaveIDone Guilt Hulk]]
*** Though Grey Hulk isn't really "evil".
* Wolverine has a tendency to lapse into a "berserker rage" while in close combat. In this state he lashes out with the intensity and aggression of a mindless animal and is even more resistant to psionic attack. Though he loathes it, he acknowledges that it has saved his life countless times.
* The New Mutant Magik, way back when, was partially transformed into a demon by Belasco. Her "Darkchylde" side is intelligent but malicious, though almost powerless on Earth, where her magic doesn't work very well. In the end it took over her and nearly ended the world in a major Crossover Event.
* It's still not clear whether Dark Phoenix is Jean Grey's SuperpoweredEvilSide or a variation on GrandTheftMe.
** Whether Jean actually ''became'' Phoenix (and then Dark Phoenix) or was merely ''replaced'' by the Phoenix Force is in an almost constant state of {{retcon}}, so the confusion is quite understandable.
* In the British Fleetway ''SonicTheHedgehog'' comics, this was how Super Sonic was. When he split from Sonic and lost his powers he mellowed out, but returned to form when he got them back. The Archie comics did a homage to this in one issue, although in that canon there's generally no personality difference between Sonic and Super Sonic.
* The Sentry and the Void, from Marvel Comics, are this trope taken to its extreme. They manifested as alter-egos of a single person, representing the good and dark sides of humanity, respectively. The Sentry is a superhero and the Void is a supervillain. They've also split into separate bodies, and sometimes make out with each other.
** ONE TIME. And immediately following this, the Sentry [[spoiler:threw the Void ''into the sun.'']] Given the Void's speech prior to this, this doesn't decrease the FoeYay any, though.
**Isn't more like ScrewYourself?
* Stephanie Maas/Critical Maas in ''Rising Stars'', in which the only normal in a town full of superheroes actually just shunted her super powers (including flight, strength, and creepy-puppetmaster mind control) into her secondary, psychopath personality.
** Incidentally, Critical Maas is undoubtedly the inspiration for ''Heroes''' Jessica/Niki, right down to [[spoiler:her history of abuse by her father]] and her penchant for calling her 'weaker' half 'little mouse'.
*Jackie Estacado in ''TheDarkness'' also fits this, and even likes it during the early parts of the series, as it gives him more unique ways to kill people.
* Mr. Negative, new [[SpiderMan Spider-Man]] villan take this to a whole new level [[spoiler: he was born when personality of some thougt divide on two parts - pure good become filantropist Martin Li, while pure evil become Mr. Negative.]] Both fights with each other in interesting way - Negative likes to corrupt all [[spoiler: Lee's]] good deeds, while [[spoiler: Lee]] helps people that suffers because of Negative.
* Curt Connors and Lizard are often potrayed this way [[spoiler: Hoever, there's a RetCon wich reveals that Connors was always in control of Lizard and left him out when life was too hard for him. He just keep teeling himself it's not truth.]]
[[/folder]]

[[folder:{{Film}}]]
* Subverted in the comedy ''The Animal''.
* Nathan Wallace in ''[[RepoTheGeneticOpera Repo! The Genetic Opera]]'' is a sweet, loving, family man. Until he puts on his helmet, at which point he becomes the merciless Repo Man.
* ''HeavyMetal'' segment "Captain Sternn". While under the influence of the Loc-Nar, Hanover Fiste grows into a mightily muscled hulk and smashes through all opposition in an attempt to murder Sternn. [[spoiler:Once everyone's gone, he turns back. Sternn then thanks him for getting him out of the trial... before shooting him out of an airlock in lieu of payment.]]
* The version of Venom in the third ''{{Spider-Man}}'' movie is, of course, Peter's superpowered evil side, and it begins to affect his personality. The catch is, Venom's just enhancing Peter's latent personality traits, so out-of-costume his evil side comes across as a massive dork, and he is generally an asshole to everyone rather than being a figure of terrible power.
[[/folder]]

[[folder:{{Literature}}]]
* Most incarnations of JekyllAndHyde in popular culture portray Hyde as inhumanly large and strong, often ape-like. (For instance, the movie ''VanHelsing'', ''TheLeagueOfExtraordinaryGentlemen'', etc.) In the [[TheStrangeCaseOfDoctorJekyllAndMrHyde original book]], there is nothing superhuman about Hyde; he simply gives free reign to his base instincts. In fact, it is explicitly stated that Hyde is smaller than Jekyll, as Jekyll is more a good man than an evil one. In the second volume of ''League'', Hyde acknowledges this, but explains that the longer he's given free reign, and the more impotent Jekyll (the "good side") feels, the more powerful he becomes.
* In ''{{Redwall}}'', some animals (usually badgers) have an attack/split personality called the "Bloodwrath" which makes them ''extremely'' powerful, very resistant to pain... and also no longer able to tell friend from foe, meaning it's dangerous to ''anyone'' who's nearby when they go into this rage.
* Johnny Truant channels his SuperpoweredEvilSide against [[EveryoneCallsHimBarkeep Gdansk Man]] in ''HouseOfLeaves''. The way in which Truant thrashes him and how the book describes Gdansk Man's wounds afterwards has led to some EpilepticTrees, such as [[spoiler:Johnny Truant '''is''' [[strike:the Minotaur]]]].
* Most [[OurWerewolvesAreDifferent werewolves]] that aren't villainous in human form get a lot more powerful and don't mind the taste of blood when transformed. Both the ''KittyNorville'' and ''MercyThompson'' series have werewolf choosing their animal form for combat, and the ''KittyNorville'' series portrays the Wolf as an alternate personality. The Wolf won't go out of its way to KickTheDog, but [[HeroicSociopath it won't really care about]] taboos regarding [[ImAHumanitarian cannibalism]] or [[ThouShaltNotKill murder]].
* Exar Kun, Darth Vader, Ulic Qel-Droma, Darth Malak... when a [[StarWars Jedi]] falls to the Dark Side, it's time to get the hell out of Dodge.
[[/folder]]

[[folder:{{Live Action TV}}]]
* Niki in ''[[Series/{{Heroes}} Heroes]]'' has her amoral alter ego Jessica ("[[FanNickname ikiN]]"), who has sole control of her super strength [[spoiler:until the finale, when Niki finally gets to use it for herself. She might have used it once on impulse a few episodes prior to stop an attacking policeman--this is debatable.]]
** In the second season, it was explained that [[spoiler:Niki, like some other metahumans, subconsciously manifest another personality imbued with their ability (leaving the original personality powerless) as a result of being metahumans, or because of the original personality's inability to cope with the reality of being a metahuman. When Niki conquered the Jessica persona at the conclusion of the first season finale, she manifested a third personality named Gina several weeks later.]]
* A really beautiful [[DeconstructedTrope Deconstruction]] is the British TV series ''{{Jekyll}}''.
* Lori developed one in the ''BigWolfOnCampus'' episode "Manchurian Werewolf" after being bit by a brainwashed Tommy. She became a member of the werewolf syndicate. Merton also got a dose of the evil life in "Everybody fang chung tonight" and "Boy who tried wolf" where he become a vampire and a werewolf.
* Pretty much every HeroicVampire protagonist or Supporting Character: see ''ForeverKnight'', ''{{Angel}}'', and ''{{Moonlight}}''.
** Angel gets listed twice because he's from TropeOverdosed ''BuffyTheVampireSlayer''.
* Kamen Rider Kabuto's "Kamishiro Tsurugi" is actually the Scorpioworm, who actually manages to [[spoiler:overpower both Cassisworm Clipeuses when he was unable to defeat even one as Kamen Rider Sasword]].
* In the live-action ''PrettyGuardianSailorMoon'', [[spoiler:Sailor Moon's alternate persona Princess Moon is pretty much a Superpowered LoveMakesYouEvil Side]].
* In the ''{{Farscape}}'' universe, starving [[PlantAliens Delvians]] start sprouting growths that paralyze any predators that touch them, turning would-be predators into prey. If that doesn't help, they'll start emitting spores, gradually paralyzing any and all lifeforms in the vicinity. In this state, higher cognitive functions are compromised, gradually turning them more and more feral. And if the said Delvian is [[TheAtoner Zhaan]] who was nice only due to her HeroicWillpower in the first place...
* ''BuffyTheVampireSlayer'' has several of these:
** If {{Angel}} loses his soul (due to the lingering effects of a GypsyCurse), he becomes the [[ChessMaster brilliant]] and formidable Angelus, widely reputed to be [[CompleteMonster the most vicious vampire in history]]. As Cordelia Chase once queried about Angelus's evident [[EvilGenius genius]] compared to his heroic alter ego's, "...what is it about [[EvilIsCool evil]] that jacks up the I.Q. points?"
** Willow has Dark Willow, which she touches whenever she taps dark magic. Easily identified by the BlackEyesOfEvil.
** Giles' Ripper persona isn't quite an example, as the Ripper is actually no more powerful than Giles, he just has fewer compunctions.
[[/folder]]

[[folder:{{Mythology}}]]
* Cuchulainn from Irish mythology has a prime example of this kind of UnstoppableRage, making this OlderThanDirt. In the epic, Táin Bó Cúailnge, he enters a "Ríastrad" or "Warp Spasm". In this state he [[PainfulTransformation transforms]] into [[OneWingedAngel a horribly mutilated monster]] whose very appearance is enough to scare enemies away. The catch is that, while in this form, Cuchulainn may not know friend from foe.
** See ''Slaine'' from {{2000AD}} to see just ''how'' mutilated.
[[/folder]]

[[folder:{{Tabletop Games}}]]
* This crops up in the various ''WorldOfDarkness'' RolePlayingGames, especially those featuring Vampires and Werewolves. One TagLine for the original ''Vampire: The Masquerade'' was "A Beast I Am, Lest A Beast I Become" -- leeches had to allow themselves little atrocities like controlled blood-drinking to avoid being consumed entirely by the madness of their inner blood-hunger.
** Werewolves, on the other hand, don't tend to view their own [[UnstoppableRage berserk frenzies]] as "evil" (after all, Rage is a gift from Luna... and they have plenty of reason to be really, really pissed off). However, if they give in to their Rage ''too'' fully, they can enter a state called "Thrall of the Wyrm," just like a normal frenzy, except that it's inescapable, and tends to provoke rather horrific behavior (typically either cannibalism, dismemberment, or... er... [[IfYouKnowWhatIMean defilement]]).
** [=WoD=] Wraith have got their Shadow, a second personality usually existing within the wraith trying to make them them give up their struggles and descend into nonexistence or permanently hand over control of their body. Depending on the Shadow, this might take many forms, some direct and some seemingly helping the wraith. The latter type often has ways to enhance the wraith's body when temporarily in control - better attributes, more magic powers or even items appearing only during the Shadow's catharsis. Such wraiths then always have the ability to let their Shadows handle combats too tough for them, but generally loathe to do so because there's no telling what else the shadow might do while in control.
** Changelings can get magic ("Glamour") from normal humans two ways - the first is by inspiring them to do something incredible. The second is to "ravish" them - make them feel despair. One example of this involved convincing a small child that the Fae in question had just ''murdered the Tooth Fairy''.
** Although not directly part of the World of Darkness, ''{{Exalted}}'' has a couple instances where the characters go temporarily insane on some level. But the Solar Exalted might have this particular category nailed; one of their abilities--Ascendant Battle Visage--places them into a battle-trance that physically changes them to reflect their BattleAura, and grants them intense and brutal combative skill. Remaining in this state too long, however, sends them into an UnstoppableRage, at which point they become even deadlier, and fight until either they're dead or everything else that might be considered an enemy is dead.
*** The Solars have nothing on the Ghost-Blooded, who (in the first edition at least) could learn a certain Arcanos called Lower Soul Ascendant, which fits this trope to a T -- increased physical power at the cost of embracing sociopathic behavior.
** The [[ContinuityReboot New]] WorldOfDarkness keeps much of this; Vampires have the Beast within, which compels them to feed. Werewolves have two degrees of rage: one where they have to kill ''something'', and another where they have to kill ''everything''.
* In ''DungeonsAndDragons 3.5'', there is a prestige class called Frenzied Berserker. Once they've Frenzied, which is like a Barbarian's Rage but moreso, they attack until either the frenzy runs out, they are incapacitated/dead, or there's nobody nearby.
* Highly common in ''{{Warhammer 40000}}'', and one of the reasons Space Marines (Grey Knights in particular) are required to pass such rigorous and often deadly mental trials as a method of prevention. The most obvious are the Blood Angels Chapter and its successor chapters, whose members are known to succumb to a condition called the Black Rage which increases their already SuperSoldier levels of strength and vitality and turns them into frothing berserkers who seek only death, often organised into aptly-named Death Companies led by skull-helmeted {{Badass Preacher}}s. [[OurElvesAreBetter The Eldar]] however create one of these ''intentionally'', inducing a form of split personality disorder so that in battle they can fight with unhindered skill and brutality while retaining absolute control over themselves the rest of the time. Then there's Chaos, which, being TheCorruption and AlwaysChaoticEvil personified, fully embraces the added power this trope provides with no concern for the consequences, because "sanity is for the ''weak''".
[[/folder]]

[[folder:{{Video Games}}]]
* Ryu, from the ''StreetFighter'' series of video games, has a power inside of him known as the "Satsui no Hadou", or Surge of Murderous Intention, which he works to suppress and was retconned as the reason that Sagat received the scar he bears on his chest. Akuma (Gouki in the original Japanese) represents someone who has fully given in to the Satsui no Hadou, and when he's not holding back, he is truly fearsome. In ''Street Fighter Alpha 3'', 'Evil Ryu' is actually a secret, playable character - a dark-skinned, red-eyed version of Ryu with some additional attacks from Akuma's movepool.
** Note that Akuma is an example of a character who has embraced the "Satsui no Hadou" but remains in control of his power at all times (he just holds back portions of it at various times). Ryu's SuperpoweredEvilSide is a result of his being unable to control the power. However, since the power still involves a willingness to kill and a more brutal mindset even when in control, he makes no effort to even try to learn how.
* In the third game in the recent ''PrinceOfPersia'' trilogy, the Prince occasionally transforms into an alter ego with a bladed chain-whip (and the skills to wield it gruesomely, out of nowhere) and who can completely regenerate whenever exposed to the Sands of Time, but at the expense of constantly deteriorating health otherwise. The Dark Prince is also a sociopath with a massive entitlement complex. Even when in the Dark Prince body, the Prince remains in control, but the Dark Prince hints that the health draining out of you is actually going into it, and that dying of this will give the Dark Prince control of the body (and, incidentally, Babylon).
* Soma Cruz in some of the later ''{{Castlevania}}'' games inherited Dracula's soul, while Alucard is his son (sort of). The emergence of their Superpowered Evil Sides are Alucard's greatest fear and Soma's bad ending.
* The Slayer from ''BaldursGate II'', a ten-foot tall spiky mass of pure murder that the protagonist ends up gaining access to. Using it results in a reputation loss, except for scripted events that force you into it. Plus there's the whole thing about it [[HeroicRROD killing you]] ([[WeCannotGoOnWithoutYou and thus ending the game]]) if you stay in that form for too long.
* Rozalin from ''{{Disgaea}} II'' manifests a Superpowered Evil Side during the storyline when her seal is broken, which turns to be [[spoiler:her former life as Overlord Zenon, complete with both memories and power, back from the dead]].
** Mao from ''Disgaea 3'' has a similar Superpowered Evil Side that can [[spoiler:go on a complete rampage in one of the endings]].
* From ''LaPucelle Tactics'', [[spoiler:Croix has his Superpowered Evil Side as the Dark Prince serving the fallen angel Calamity.]]
* Iori Yagami in ''TheKingOfFighters'' is normally amoral, and (judging from his winposes) has quite a few screws loose. Riot of the Blood Iori, however, has absolutely no sense of self-restrain and will attack anything on sight.
** Leona also fits this trope, sometimes even more perfectly than Iori, due to the fact that she is in the "good side", while Iori can't decide himself; with some EmotionlessGirl spices added, though that said, she has smiled [[http://www.vgmuseum.com/end/neogeo/b/kof96ika-35.gif once]].
* Jaster Rogue in ''RogueGalaxy'' does this, although his "evil" side isn't so much evil as so far above everyone else that he [[AGodAmI barely notices they exist]]. Hard to tell the difference from the "normals" point of view, though.
* Johnny Garland gains this far into the third ''ShadowHearts'' game. [[spoiler:Johnny actually died at a very young age along with his sister, Grace. Their father managed to get his hands on the series' {{Tome of Eldritch Lore}}, in hopes of resurrecting them. He only succeeds in reviving Johnny, as his sister gives up her humanity in order to save him, leaving her an empty shell, "Lady". Because Johnny's body is composed of both "Malice" (negative energy) and "Will" (the human soul/spirit), after being fatally wounded by Killer, his "true" Malice form, the Awaker, emerges.]]
* In ''{{Xenogears}}'', one of the primary villains for the first half of the game, Id, [[spoiler:turns out to be an alternate personality of the primary hero, Fei. Id was completely different from Fei in appearance (except for the face itself) and had several magnitudes more power than him.]]
* And how can we forget Zero of the ''MegaManX[=/=][[MegaManZero Zero]]'' series who gains several powerful new abilities whenever he is controlled by TheVirus.
* Elena's alternate personality Millenia from ''{{Grandia}} II''.
* Anti-Sora from ''KingdomHearts 2''. Ironically, while Anti-Sora looks ''damn cool'', he's not actually much more powerful than Sora in terms of offense, and can do nothing other than attack solo in a frenzy of clawing and kicking. The inability to heal, gain experience, or really do ''anything'' else makes this form a liability, and it can't be entered deliberately.
** That's more of an example of Sora's [[SuperMode drive forms]] occasionally being BlessedWithSuck, since Sora is still in complete control of himself; he just [[spoiler:happens to look like a heartless]] for the duration. Riku, on the other hand, plays this trope straight in all four games, but primarily in ''Chain of Memories'' [[spoiler:when you can play as him and "Dark Mode" is one of his key abilities]].
* In ''MetroidPrime 3: Corruption'', Samus gets the ability to enter Hypermode, fueled by the evil substance known as Phazon. Staying in this mode for too long corrupts her, leading to a NonstandardGameOver, specifically turning into another Dark Samus.
* Dark Jak from ''JakAndDaxter'''s attempt to become DarkerAndEdgier.
** Although interestingly subverted by Light Jak in Jak 3... which is a superpowered GOOD side.
* [[SonicTheHedgehog Sonic the Hedgehog]] has one in ''SonicUnleashed''. At night, he'll turn into Sonic the Werehog, a bulky werewolf-esque form of himself with super strength and stretchy arms. Though his personality remains more or less the same except for the obligatory howling.
* In ''SuperSmashBros Brawl'', Bowser's Final Smash transforms him into the even more monstrous Giga Bowser, although he was evil to being with, [[IneffectualSympatheticVillain kind of]].
** Giga Bowser is pretty much Evil Bowser since Bowser isn't much of a villain these days (he's been taking a back seat to eviler people recently).
** In the RPG's anyway, he's still evil in the main series.
* Almost every member of the Mishima Family in the ''Tekken'' series. Also Ogre/True Ogre.
** Only Jin adheres to that fully with Devil Jin, however. Kazuya was evil all along, calling his Devil Form would be more like normal Super Powered self. And Heihachi is just that evil, [[BadassNormal he doesn't need an evil side to get more evil, super powered or kick ass]].
** Jinpachi could be said to be another example, as he holds the King of Iron Fist Tournament 5 to find somebody to stop him, as he could feel the Devil taking over. He also sends a letter to Wang, his old friend, to have a go as well.
* In the early ''[[SoulSeries Soul Calibur]]'' games, Nightmare was supposedly a Demonic-Sword-induced version of this for Sigfried. The latter freed himself in [=SCIII=], but his armour and residual evil power was [[EnemyWithout too attached to Soul Edge to die]].
** Two far more definitive examples show up in [=SCIII=] as the boss [[NightmareFuel Abyss]] (spawned from Zasalamel's quest for the power to die), and bonus boss [[SNKBoss Night Terror]] (Nightmare on serious 'roids).
* ''Fighters Destiny'' has a clown character, and there's a cheat you can use which turns him into a werewolf.
* ''{{Primal}}'' has its main character who personifies this when in any of her monster forms.
* Subverted in ''Muppet Monster Adventure''.
* It is revealed in ''[[DotHack .hack//GU]]'' that Natsume has a split personality: Her normal self is her cheery, slightly ditzy self while her other self is crazed, rampaging Pker known as The Edgemaniac. This is played for laughs.
** In the movie adaptation, Haseo's B-St Form is basically this trope incarnate. [[TheWorfEffect Even if all it did was make him look pathetic against the final boss...]]
* Vincent Valentine from ''FinalFantasyVII'' can transform into a variety of monstrous forms using his limit breaks. Possible forms include Frankenstein's Monster, [[AxCrazy Jason Voorhees]] and Chaos, the BigBad of the first game in the series.
* Django, the gun-slinging hero of ''{{Boktai}}''. In the second game of the series Django is infected with vampirism and almost loses his soul before his half-brother Sabata purifies him with the Solar Pile. After this, Django eventually gains the ability to transform between human "Red Django" and vampire "Black Django." Though it might be argued that Black Django isn't that much more powerful as, despite his dark-based powers, he loses the ability to use all of Django's magic (gaining new spells only he can use) and is harmed by both rain and sunshine.
* The Terror Mask in the ''{{Splatterhouse}}'' series embodies this trope, especially in ''{{Splatterhouse}} 3'' where its own personality, and its effect on Rick, become more apparent.
* In ''Majora's Mask'', Link can trade all of the masks in the game (no mean feat, mind you) to turn into a Badass infused with the power of an angry god. Sweet, innocent little Link can then tear through any boss in the game with little difficulty. However, the mask can 'only' be used against bosses without using a cheat.
* Queen Arshtat Falenas in ''SuikodenV'' took the [[BlessedWithSuck Sun Rune]] into her to prevent it from falling into the "wrong hands." Ever since, she [[PurpleProse melodramatically rants]] and [[NoblewomansLaugh cackles authoritatively]] whenever her "divine rule" is threatened. Once, she even unleashed the Sun Rune, completely dessicating a lake and its nearby landscape and leaving her nearby subjects to die a wasting death. All in all, a SuperpoweredEvilSide is a great way to balance TheHighQueen and her [[GodSaveUsFromTheQueen darker counterpart]], leading to a natural [[TheWomanWearingTheQueenlyMask aloof regality]].
* In ''TheWorldEndsWithYou'', the BonusBoss is the Noise form of [[spoiler:Hanekoma]], and since he ''really'' kills you if you .lose, it can be seen as this. The fact that, during the fight, he [[spoiler: spews his human form's inspirational phrases like battle cries]] could show that he's not quite in control.
* Emil from ''TalesOfSymphonia: Dawn of the New World'' has Ratatosk mode, where he morphs from a [[TheWoobie Woobie-ish]] NonActionGuy into an ur-BadAss AntiHero BloodKnight. [[spoiler:It's not so much that Ratatosk is Emil's SuperPoweredEvilSide; instead, Emil is Ratatosk's NonActionGuy side. Like the case in ''ElfenLied'', the "evil" side is the original person]].
* At one point in ''{{Wild ARMs 2}}'', Ashley is transformed into some kind of zombie-like creature early on, but before he is taken completely, he makes it to the [[SwordInTheStone Argetlahm]] and pulls it out -- this has the result of countering the demon within him with the good force of the sword, and the resulting combination is a badass black-armored-red-trimmed entity called Knight Blazer. He can't actually use it in battle until a few plot points later, but once he gains the ability, nearly every remaining boss fight in the game boils down to letting him transform in order to open up a can of whoop-ass. [[spoiler:At one point, in a moment of UnstoppableRage fueled by [[HeroicResolve a terrorist threatening his girlfriend]], Knight Blazer actually [[TookALevelInBadass takes another level in badass]] and transforms into a gold-armored knight with extra abilities that is that much more powerful. And then at the end of the game, the "demon" portion escapes Ashley's body and reveals itself to be the CosmicHorror responsible for devastating the world centuries ago, Lord Blazer. Of course, this leaves Ashley with the holy sword. Guess who wins [[ThePowerOfFriendship the]] [[ThemeMusicPowerUp resulting]] [[CrowningMusicOfAwesome boss]] [[CrowningMoment/VideoGameBosses fight]].]]
* In 'MegamanBattleNetwork 4'', if [=MegaMan=] turns dark enough from the use of dark chips, his dark side will appear after he is K.O.'d and start fighting. [=MegaMan=] gains control back after a while.
** Chaos Shadow Soul in ''BattleNetwork 5'' made MegaMan completely invincible and uncontrollable as the AI attempted to duplicate the player's fighting style. Speaking of which, the fight against Dark Rock in ''Battle Network 4'' did the same, using every chip the player had ever used and weighting the ones the player used more often.
* In the Heaven's Feel route of ''FateStayNight'', Sakura Matou's SuperpoweredEvilSide is powerful enough to defeat [[spoiler:True Assassin, Gilgamesh, and Zouken Matou]].
* In ''TheSuffering'', you get to change into some... monster thing that can tear enemies (body horror like freaks of death and human atrocities). It is implied that your character does not actually transform, instead he goes into a rage that boosts his strenght. But then how does he make spikes pop from the ground...?
* The Fierce Deity Mask (called the "Oni Mask") in ''LegendOfZelda: Majora's Mask'' is treated as one of these in {{Fanon}}; canonically, at least the Skull Kid thinks it's the mask of a "bad guy".
* ''LegendOfMana'' has two characters who have a Superpowered Evil Side: [[spoiler:Pearl has Blackpearl, what she was like pre-LaserGuidedAmnesia]] and [[spoiler:the Mana Goddess]].
* In ''Painkiller'', when you collect 66 souls of enemies you killed, you transform into an unstoppable demonic killing machine. It only lasts for about 30 seconds but that's all the time you'll need to obliterate an area full of monsters just by ''looking'' at them.
* It may not be on quite the same level, but in ''[[{{Pokemon}} Pokemon Colosseum]]'', there's a random chance that a Shadow Pokemon might go into 'Hyper Mode' during a battle. The Pokemon in question will be surronded by a black aura, and will do more damage - BUT. It won't be able to use any moves you've unlocked, it can't be healed, and it will also take recoil damage when it attacks. Thankfully, you can [[SayMyName call out to it]], which brings it back to it's senses.
* Jin from ''BlazBlue'', normally a smug, arrogant JerkAss, goes ''[[AxCrazy completely berserk]]'' when in combat, especially if his opponent happens to be [[CainAndAbel Ragna]].
[[/folder]]

[[folder:{{Web Comics}}]]
* Roger in ''CollegeRoomiesFromHell''. Unleashing his werecoyote side is often the Roomies' only way out of a tight spot, but he has trouble controlling it, and he's been warned by another werecoyote that sooner or later he'll be unable to change back.
** He actually has a second werecoyote form that is a stronger embodiment of this trope.
* Graveyard Greg of the ''Gaming Guardians'' has two separate and unrelated evil sides. Not only is he a werewolf, with an animalistic but self-aware wolf personality, but he's also possessed by a voodoo spirit which can take control of him at times. Greg has retained control by pitting them against each other, until they decided to team up to suppress him, becoming a zombie wolfman which calls itself "Mange".
* ''LastResort'' has Jigsaw, since apparently [[OurVampiresAreDifferent all vampires in her galaxy]] can transform during their UnstoppableRage.
* In ''JACK'', the eponymous character, a personification of the sin of Wrath and the Grim Reaper, will occasionally enter a kind of "Wrath Mode". In this state, he will be overcome by his sin and gain a boost of power. He later [[spoiler:absorbs and seals the sin of Lust, who talks to him, hassles him and will sometimes help him in fights through his cloak.]]
* While 'Fallen Grace' (AKA 'Dark Omega Grace') from ''ElGoonishShive'' falls much closer to the CrouchingMoronHiddenBadass type, she still deserves mention here. Not only is Fallen Grace actually willing to use her shape-shifting powers as a weapon - unlike the pacifistic (NOT TechnicalPacifist) Grace - she's also got access to the Lespuko Spurs; special claws that retard healing, thus neutralizing the advantage of the HealingFactor. She's also got horns, HellishPupils, and [[SpikesOfVillainy a whole lotta spikes]].
* In ''{{Gnoph}}'', Will's symbiotic partner Lyss usually acts as a [[BondCreatures Bond Creature]]; but when he passes out and she takes full control of his body, she acts like an example of this trope, due to being AxCrazy and having no compunction against killing (or ''[[ImAHumanitarian eating]]'') humans.
* Subverted in ''OrderOfTheStick'': It initially looked like the comic was going down this path when Vaarsuvius made a [[DealWithTheDevil deal with three devils]] in order to save the lives and souls of [[AmbiguousGender his/her]] family. Having successfully rescued them from a dragon, (s)he then proceeded to [[spoiler:use epic magic to slaughter as many as a quarter of the black dragons in existence, in what was widely held to be a MoralEventHorizon by the audience.]] The next strip reveals that, contrary to what the devils said earlier, the power-up had no effect on Vaarsuvius' ethics and that whatever atrocities (s)he just committed were all of his or her own doing.
* Black Mage from ''[[EightBitTheater 8-bit Theater]]'' has one of these. Considering that he's ''normally'' an OmnicidalManiac with enough power to destroy entire cities, this should tell you something.
** And now, [[spoiler:omniscient superwizard Sarda has absorbed Black Mage's superpowered evil side]]. {{Lampshaded}} thus:
--->'''[[spoiler:Sarda]]:''' Who ''knows'' what kind of sadistic and impossible stuff I'll do now.
[[/folder]]

[[folder:Web Original]]
* A fairly goofy example occurs in episode 40 of ''RedVsBlue'': in order to fight off a horde of "noobs" in Battle Creek, Caboose gets in touch with his "angry side", which results in him gunning down the noobs while shouting bizarre threats like "I will eat your unhappiness!" and "Your toast has been burned, and no amount of scraping will remove the black parts!"
-->'''Caboose''': Now I'm thinking of a kitten... covered in spikes... that makes... me... angry... YYAAARRRRGGHHH!
-->''Caboose jumps off the roof he was hiding on, shaking the ground when he lands''
-->'''Caboose''': My name is Micheal J Caboose, and [[ThisIsSPARTA I. Hate. Babies]]!
-->'''Red Zealot''': It's the beast! The Anti-Flag! Come to live among us and rule for seven years! The end is nigh- blleergh!
** He did this by replicating the effects of being possessed by the AI O'Malley, who gives whoever he inhabits a Super-Flanderized evil side, which in Tex's case makes her super aggressive. When he inhabited Grif he wanted to Take Over The World, but was too lazy to do anything. Only Church is immune to this effect, being as cynical as it is possible to be already. [[CerebusRetcon Among other reasons...]]
* In ''TalesOfMU'', the side of Mackenzie that some fans have taken to calling Kenzie is two details off from being a textbook example of a Superpowered Evil Side: First, Kenzie is triggered by hunger instead of desperation in battle. Second and more distancing, the closest thing to a superpower Kenzie has over normal Mack is ''[[LawfulStupid being willing to hurt people that are trying to kill her]]''.
* Shandala in ''BrokenSaints'' has [[BreakTheCutie some]] [[BewareTheNiceOnes serious]] [[NightmareFuel issues]].
In the DCU role playing universe of JLA Watchtower/DC Nation, [[BewareTheNiceOnes Fauna]], a sweet, quiet [[GranolaGirl Granola Girl]] shapeshifter has this problem if you [[BreakTheCutie push her too far]]. Also, the more complicated her shapeshifting or extensive the use of her other abilities, [[TheMindIsAPlaythingOfTheBody the more feral she becomes]].

[[/folder]]

[[folder:{{Western Animation}}]]
* In the ''TeenTitans'' cartoon, a splashing of chemicals prompts good-natured vegetarian Beast Boy to turn into a surly, meat-chomping bad boy who later turns into an anthropomorphic wolfman that was capable of taking on the entire team (as well as another wolfman). Later it's explained that, instead of turning Beast Boy into an actual lycanthrope, the chemicals only unleashed what was already there, and he's given an antidote so that he won't transform against his will. He once again manifests this hidden wild side in a battle against Slade, slicing through a number of his goons before Slade puts a stop to it with his own supercharged powers.
** Possible subversion: It's made quite clear that "Man-Beast" isn't evil, just a really powerful, rather intelligent animal. Like any animal, it becomes hostile when scared, but generally it keeps to its human form's wishes. Beast Boy still expresses concern that it's still inside him at the end of the episode.
** And of course, there's Raven's 'Daddy Issues'. Dr Light should ''really'' have backed off like she told him.
* ''KimPossible'': Ron Stoppable is ordinarily a likable goof, but he's been zapped a couple of times with AppliedPhlebotinum with superpowered evil results. The first time, the device was malfunctioning and gave him a transfusion of Dr. Drakken's evil, turning him into the insane, fiendish, blue-skinned, cleverer-than-Drakken-by-a-long-shot "Zorpox the Conqueror." The second time, the device was a properly-working instant FaceHeelTurn button. One might simply chalk it up to a removal of inhibition, of course, as Ron has some serious mystical mojo that backs him up at critical instances. The point is, Ron's evil side is inexplicably hyper-competent to the point of being slightly unnerving (enough to cow Shego into obedience) -- he mastered the art of having multiple plots within what may well have been hours of his conversion, and showed himself to be a serious, focused martial artist, at least the equal of Kim. Granted, he HAS had secret ninja training...
** Ron loses focus easily, his evil side doesn't. When Ron gets focused, he becomes competent. But where the heck did his evil side get the skills to invent that plasma catapult thingy?
** Actualy, Ron is an intuitive genius. In other words, he is actually very intelligent, he just isn't aware of it, and has a hard time learning something that doesn't interest him. For example, his vocabulary, it is by far the most sophisticated of the cast, which he picked (probably) from movies: "Keep your friends close, and your enemies closer" a quote that Ron took from maquiavel. Also, his doom machine, that Drakken threatened him to do, actually worked, and was made from scrap parts. Moreso, it was actually {{Lampshade}}d in the movie a Stitch in Time, where kindergarten Ron made a complex speech. WordOfGod actually suggests that he may have repressed his genius so as to fit in better.
** He channels negative emotion into action alot better than positive happpy emotion. Taking over the world is a negative emotion. He also channels his powers when someone hurts Kim. He just does alot better when in angry mindframe.
* Another AppliedPhlebotinum instance is Rhinox being turned into a Predacon in the ''{{Transformers}}: Beast Wars'' episode "Dark Designs". He's an ideal minion on the surface, but beneath it, he's cunning, capable, and extremely aggressive, quickly taking it upon himself to create chaos in a takeover bid, which almost works until Megatron applies ReversePolarity to the AppliedPhlebotinum just in time to keep Rhinox from finishing him off. Good thing for Megs that Evil Rhinox just had to [[EvilGloating gloat like any other bad guy would have, huh]]?
** Another example involving Rhinox shows up in ''BeastMachines'' when [[spoiler:it was revealed that Tankor, TheBrute tank that had been hounding the Maximals all season was really Rhinox in a sort of BrainwashedAndCrazy situation. Sadly things got even worse after Optimus Primal freed him from Megatron's control and he turned against his former allies and started a XanatosGambit to take over Cybertron.]]
** Some poor, misguided fools seem to have heard that [=G1=] Grimlock is capable of combining with the Dinobots to create "the Beast," a terrifying titan of destruction and primal rage. '''These people are damned liars.''' Or at least, weren't [[http://tfwiki.net/wiki/The_Beast_Within aware]] that the [[SoBadItsHorrible sheer suckitude]] of that StoryArc was so much that Unicron and the Autobots teamed up to [[DisContinuity wipe it from space and time]].
* A more literal form of this is ''TheBatman'' version of Clayface. Just using his powers turns him insane and monstrous.
* In ''EarthwormJim'', whenever Jim's puppy sidekick Peter is injured, he turns into a hulking, ravenous mutant whose sole goal in life seems to be beating Jim to a pulp. In a joke inversion, Peter's EvilTwin is evil when "normal", but his psycho mutant form turns out to be ''good''.
* The 2006 revival of ''BikerMiceFromMars'' has Stoker turn into an insane rat-like beast called Stoker rat.
* An episode of ''Mr Meaty'' had Parker (who is normallly calm under pressure due to the fact he just blissfully takes all those insults people kept throwing at him in) turn into a Hulk-like monster due to being unable to hold all those insults in any longer.
* ''AvatarTheLastAirbender''. Granted, the Avatar State isn't evil per se, but it is also very uncontrollable and violent. The main character ''never'' kills anyone unless he is in the Avatar State. Also subverted a little bit in the 3rd season when [[spoiler:Zuko executes his HeelFaceTurn and sees a significant powerdown in his firebending as a result of no longer being constantly angry. Then he and Aang meet a few dragons and suddenly Zuko's firebending is more powerful than it ever was. He found the good method of channeling.]]
* [[spoiler:Sari]] gains one in the season 3 premiere of ''TransformersAnimated'', though not neccesarily ''evil'', per se, just uncontrollable.
* In an episode of ''The New Adventures of Batman'' (the one after ''BatmanTheAnimatedSeries''), Batman inhales an anti-fear toxin made by the Scarecrow. As a result, Batman has no fear. NONE. At one point, Bruce Wayne (that's right, no disguise) infiltrates some facility and has to deal with a moat with an alligator or crocodile. He walks through the moat, becoming completely submerged. While still under water, sends the animal flying from the moat and continues on his merry way.
[[/folder]]

[[folder:{{Real Life}}]]
* The nigh-mythical Norse berserker rages, an adrenal and psychosomatic overclocking which gave one the ability to ignore mortal injuries but removed one's ability to distinguish friend from foe. The less brave soldiers simply drank a lot of alcohol.
** However there is little consensus as to how effective the rages were, or if they even existed, some historians attributing these accounts to overwhelming fear of the Norseman, a likely scenario considering the Norse's tendency to attack and loot monastaries (being non-Christian and thus seeing no importance in them other than being very wealthy), which was the feudal equivalent of crossing the MoralEventHorizon.
[[/folder]]

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