The case where a being is able to engage in superheroics or grand villainy not by gaining any powers or by being a BadassNormal, but by being a vessel in some fashion for another personality that does have superpowers, but only when that personality takes control.

This personality can also look and be physically very different. This takes several superhero/villain issues and solves them in a single stroke. They don't need a disguise because you wouldn't be able to tell by looking at them. Normally, however, writers will not remove the issue of being discovered; they'll use the single moment of transformation as a time where the secret can be discovered or requires the hero diving off into that phone booth. They just don't have to constantly worry about the issue. They can keep the superhero relatable by having the non-powered character be TheEveryman or OrdinaryHighSchoolStudent. They also won't have the same "using your powers for selfish gain" issue because a complete personality change can be used so easily.

The transformation can often be handled by a TransformationSequence. Issues about how the personality is split off can vary. Sometimes it's like it's just another person hiding inside their body until the right moment, other times it's a total personality shift but they'll retain the memories of being that Superpowered Alter Ego and it will still be them. Maybe some FanWank, or even deliberate ambiguity, will occur over how much the alter ego is a separate personality at all or whether it's more of a SuperMode or HenshinHero with a confidence boost.

When the superpowered side is evil, then it is, rather unsurprisingly, the subtrope SuperPoweredEvilSide. This trope itself is the subtrope of SharingABody.



[[folder:Anime & Manga]]
* ''Manga/DNAngel'' is based around the main character, Niwa Daisuke, having a long family tradition of being possessed during their adolescence by 'Kaitou Dark,' a supernatural famous art thief. He's tall and handsome where Daisuke is short and cute, and does not act a few hundred years old by any means. [[spoiler: But killing the stuff they steal is saving the world or something,]] so it's reasonably heroic. Mostly his real super powers don't get used much, because it takes a lot out of Daisuke when they are.
** HilarityEnsues whenever accidental transformations happen (it's set off by his 'heart pounding' in connection with the girl he likes), especially at school. Occasionally it will be Daisuke in charge of Dark's body, but when things get really sticky is when Dark is running things but looks like Daisuke.
** Daisuke's mother was heartbroken that she, as a girl, wasn't able to be Dark, so she fixed on having a son who was and runs his 'career' capably. Tennis Mom of stunt robbery.
* Sort of used in ''Manga/CardcaptorSakura'' with Yukito and Yue; Yue's a magic-using WingedHumanoid, while Yukito is his "false form" that (presumably) Clow created for Yue to hide in while waiting for the Final Judgment. Besides that, Yukito is a normal teenage boy who is unaware of his superpowered true form.
* ''Manga/BirdyTheMighty'': Tsutomu can't use the powers of Birdy, even though it's technically her body, but they can communicate and switch with a moment's notice (without invoking a HenshinHero) once they've agreed they need to work together. Sometimes though, Birdy just steals him away when she needs to run off to do her work.
* The eponymous character(s) of ''Anime/YuGiOh'' is/are this; upon solving the [[AncientArtifact Millennium Puzzle]], Yugi Moto becomes host to the soul of an ancient unnamed pharaoh, who apparently is even better than Yugi is at children's card games. The pharaoh also looks [[InexplicablyIdenticalIndividuals almost exactly like Yugi]], but is slightly taller and more mature. While not super-powered per se, the 3-5000 year old pharaoh has an almost [[GambitRoulette supernaturally]] good grasp of the [[TheStrategist strategy]] of [[XanatosSpeedChess gaming]], and confidence to match. Oh, and he can [[MindRape attack people's minds]] with his [[ThirdEye forehead eye]].
** [[WebVideo/YuGiOhTheAbridgedSeries Is "mind crush" your answer to everything?]]
** Played with, at least in the [[Manga/YuGiOh original manga]]. One of the themes of the story is that Yugi is stronger than he thinks, being able to surpass his counterpart in some ways (for example, in terms of morality); in the end, [[spoiler: it's demostrated through the Ceremonial Battle he's able to surpass Yami in every way, including games.]]
* ''LightNovel/KyoKaraMaoh'' has Yuuri's Demon King side, which possesses the ability to actually use the demon magic that's his by birthright. He only comes out when Yuuri is really upset by some form of injustice.

[[folder:Comic Books]]

* [[ComicBook/{{Shazam}} Captain Marvel]] is the Superpowered Alter Ego to 10-year-old audience surrogate Billy Batson. In UsefulNotes/TheGoldenAgeOfComicBooks they were definitely separate personalities. Nowadays, however, after ''ComicBook/CrisisOnInfiniteEarths'', Marvel is a SuperMode of the same child personality who acts often in a very childlike and innocent way, but there is still some noticeable change due to the addition of the Wisdom of Solomon to the character.
** That said, some AlternateUniverse versions - e.g., ''ComicBook/TheMultiversity: Thunderworld'' and ''ComicBook/{{Convergence}}: Shazam!'' - keep Billy and Captain Marvel separate personalities.
* ''Deadman'' has shades of this; he's a ghost who can possess people, granting them his acrobatic skills and reflexes, and giving him whatever abilities the host may naturally possess.
* Creator/DCComics' [[ComicBook/{{Etrigan}} The Demon]]
* DC Comics' ''ComicBook/TheCreeper'', who supposedly inspired ''WesternAnimation/{{Freakazoid}}'' (see below).
* One version of Rose and Thorn. They didn't even ''know what the other was doing,'' and had to write to each other, Rose leaving a message to tell Thorn who needed a good butt-kicking.

* ''ComicBook/TheMightyThor'' does not have a conventional secret identity. Rather, he exchanged places with a mortal much like DC's Captain Marvel (above). This has been subject to occasional exceptions (such as during Walt Simonson's run), but Thor existing without his mortal counterpart never seems to last long.
* Similar to the Mighty Thor example, one time Rick Jones and ComicBook/CaptainMarVell were united by negabands, and only one could exist in the "real world" at a time, the other being transported to the Negative Zone. This meant you had a teenager apparently transforming into an older, wiser superhero named Captain Marvel. Yes, he ''did'' [[ShoutOut say 'shazam' when switching once]]. The writer, Roy Thomas, intentionally made the relationship between the two into a reference to the Distinguished Competition's [[ComicBook/{{Shazam}} Captain Marvel]]/Billy Batson relationship. How Marvel's lawyers explained it to DC is a mystery.
** A similar negaband process linked Rick Jones and Mar-Vell's son Genis-Vell, Marvel's third Captain Marvel.
** In the 1970s Carol Danvers (eventually Captain Marvel herself), would be replaced by a Kree alter ego with noticeably shorter hair and a completely different personality when she transformed to ComicBook/MsMarvel.
* Creator/MarvelComics' ComicBook/{{Sleepwalker}}.
* The Comicbook/IncredibleHulk centers around a human who transforms into the powerful Hulk. The Hulk is portrayed as being an independent entity, and the extent to which Hulk and Banner share perceptions and experiences changes depending on the author. Some authors depict Banner as being aware of the Hulk's actions, but others do not. Some authors, such as Peter David, have attempted to combine Hulk's various personalities but these never last long.
* Aurora and Jean-Marie of ComicBook/AlphaFlight. Jean-Marie is shyer and Aurora is more butt-kicking, though to what degree each has these traits is DependingOnTheWriter.
* Johnny Blaze, the first Comicbook/GhostRider, was like this, originally being possessed by a demon when in his Rider form. Danny Ketch, the second Ghost Rider, also had shades of this but his was the ghost of a distant ancestor seeking vengeance. Then both of them were retconned to have their powers be angelic in nature with it zig-zagging back and forth if they had control over the powers or if the powers came with another personality.
* The ComicBook/Marvel2099 version of Comicbook/CaptainAmerica in ''{{Comicbook/Secret Wars|2015}} 2099'' is a mild-mannered and pacifistic woman named Roberta who is completely unaware than danger or a trigger phrase can cause her to gain instant muscles and a hard but heroic personality. Her fellow Avengers (and her husband, who is secretly Alchemax Operative One-Nine-Four-One) work to keep this from her. Captain America, meanwhile, knows she turns into Roberta, but sees them as different people.
-->'''Captain America''': I have difficulty with ... informality.
-->'''[[Comicbook/SpiderMan2099 Miguel Stone]]''': Funny, Roberta doesn't.
-->'''Captain America''': Yes, well ... I'm ''not'' Roberta.

[[AC:Dark Horse]]
* This is the shtick of ''ComicBook/TheMask'' alongside a MaskOfPower.

* NegativeContinuity means they go back and forth on it a bit, but generally speaking ''Comicbook/TheDandy'''s ''ComicStrip/{{Bananaman}}'' is portrayed as having a notably separate personality from Little Eric, the schoolboy who transforms into him by eating bananas. For one thing, Eric occasionally seems to be quite intelligent.

[[folder:Fan Works]]
* In Creator/RoseOfPollux's ''Metamorphosis'', [[spoiler: the Chameleon-arched Jamie's]] alter-ego, who claims the title of [[spoiler: the Piper]], can be seen as this. He's seemingly smarter and more physically hardy, but significantly less compassionate than [[spoiler: Jamie]].
* In the ''Series/BuffyTheVampireSlayer'' one-shot ''[[ You Gotta Have...]]'', Buffy Summers isn't the Slayer. Rather, her split personality Faith (who looks the same as canon) is. Faith has some awareness of Buffy's actions but Buffy doesn't seem to have any awareness of Faith's.

* ''Literature/WildCards'': Captain Trips is a renowned biochemist and a burned-out hippie, with the ability to use various drugs (usually derivations of psychoactive drugs such as LSD) to transform into several other forms, each with their own powers and individual personalities.
* The titular ''Literature/CaptainUnderpants'' is a FlyingBrick in his superhero identity thanks to him drinking "Super-Power Juice". As his normal alter-ego Mr. Krupp, he's just an angry fat guy who doesn't demonstrate superpowers due to his identity being a product of [[HypnoFool botched hypnosis]] and presumably not knowing about his powers.

[[folder:Live Action TV]]
* Glory from ''Series/BuffyTheVampireSlayer'' is a deity from another dimension who can only exist in this dimension by hitching onto a person born specifically to hold her in this dimension. [[spoiler:Ben]] has to constantly find himself waking up miles away with no memory of what has happened due to Glory taking over his body whenever she likes.
* ''Series/{{Heroes}}'' has a couple of characters with a power-dependent personality disorder, such as Niki/Jessica. Niki/Jessica depicted the switch between the two with the tropes of Dissociative Identity Disorder ''a la'' Film/PrimalFear,Film/TheThreeFacesOfEve and Film/Sybil, aside from a brief flirtation with the idea that this was a twist on genuine D.I.D. with Jessica being the ghost of Niki's sister.
* ''Series/KamenRiderDenO'' combines this trope with a benevolent form of DemonicPossession. The normally meek main character Ryoutarou is assisted by four Imagin, which are humans from an erased timeline who only exist in a spiritual form. These Imagin have the ability to possess Ryoutarou, giving him entirely new powers. These range from SuperStrength, a CompellingVoice and the power to force people to dance.
* The Ultramen from the ''Franchise/UltraSeries'' are alien heroes who merge with human hosts. The extent to which they are "Alter Egos" varies from show to show.
** Series/UltraSeven and Series/UltramanLeo merely take human form rather than merge with one.
** Averted when the originals turn up for team-ups in later series -- apparently, Series/{{Ultraman}} through Series/UltramanEighty liked their hosts' forms well enough that they'll take them when they're on Earth and need to operate quietly.
** The Heisei series (''Series/UltramanTiga'', ''Series/UltramanDyna'', ''Series/UltramanGaia'') mostly do away with this.
** The original Series/{{Ultraman}} was something of an anomaly though, as it was never completely clear to what extent Hayata and Ultraman's personalities were merged as "Hayata". The implication seems to be that it's really Hayata the whole time, but he got his memory erased as a side-effect of being brought back to life at the end of the show.

[[folder:Tabletop Games]]
* Rich Burlew (of ''Webcomic/TheOrderOfTheStick'' fame) created a base class, the [[ Champion]], that applies this trope to [[TabletopGame/DungeonsAndDragons D&D 3.5]].

[[folder:Video Games]]
* In ''VideoGame/TalesOfSymphoniaDawnOfTheNewWorld'', Emil gains enhanced fighting abilities when in Ratatosk Mode. Additionally, his [[RedEyesTakeWarning eyes turn red]] and his voice deepens. [[spoiler: [[InvertedTrope However, it turns out to be an inversion]]: Emil is actually an Underpowered Alter Ego that Ratatosk fabricated so he could recuperate after almost being killed.]]
* In ''[[VideoGame/TearsToTiara2 Tears to Tiara 2]]'', the goddess Tanit is one to the goddess Ashtarte. Tart tells everyone Tanit is her older sister that she summons. Tanit is more powerful, beautiful, calm, tranquil, and wise.

[[folder:Web Original]]
* In ''Series/{{Noob}}'', the group's incompetent healer Sparadrap sometimes gets "borrowed" by his usual player's younger and much more competent brother. With the series happening mostly in DeepImmersionGaming, it plays out as if Sparadrap had two personalities : that of his usual player most of the time, during which he's completely useless, and that of his younger brother, who can actually use his abilities correctly, making him able to fend for himself and help his guildmates.

[[folder:Western Animation]]
* ''WesternAnimation/{{Freakazoid}}'' doesn't make it explicit, but his personality is meant to be the sum result of the Internet (fortunately it's the mid-1990s and the Internet didn't quite have the bit rate yet for its [[TheInternetIsForPorn major purpose]]) and he flips back and forth between the superpowered nutbag Freakazoid and the very different personality of Dexter Douglas. In the first episode, Freakazoid describes himself and Dexter as "different parts of the same whole", but they're more often portrayed as effectively separate people SharingABody.
* Later incarnations of the ''Franchise/MastersOfTheUniverse'' franchise depict He-Man as being a lot taller and more muscular than his civilian alter ego, Prince Adam.
* The ''WesternAnimation/TheAvengersEarthsMightiestHeroes'' version of the Hulk really takes this all the way. Hulk and Banner are definitely two different people and can talk to each other. As you can imagine, the Hulk is not a terribly good listener... but this incarnation of the Hulk is more sapient than most other versions and can be more reasonable than you would expect.
* [[NonPoweredCostumedHero The Blue Spirit]] from ''WesternAnimation/AvatarTheLastAirbender'' inverts this by forgoing the ElementalPowers that he uses under his SecretIdentity.