[[quoteright:335:[[WesternAnimation/BatmanBeyondReturnOfTheJoker http://static.tvtropes.org/pmwiki/pub/images/DeeDeeTwins_3205.jpg]]]]
[[caption-width-right:335:[[Literature/TheShining Come play with us, Batman.]]]]

->'''Gemma''': Are you thinking what I'm thinking?\\
'''Gem''': When ''aren't'' I thinking what you're thinking?
-->-- ''Series/PowerRangersRPM''

Sometimes a writer wants to include twins as characters but doesn't want to give them different personalities. They're just "the twins", for the most part, and even though they might have different first names, they're essentially the same character. The twins aren't really the CreepyTwins or users of TwinTelepathy; they're written just one character in two separate bodies and have only one personality between the two of them. There's no real difference between the two, and they're generally presented as one consciousness split between two bodies and are ''never'' apart.

The polar opposite of PolarOppositeTwins. If they're on a superhero or villain team of some sort, they'll often be counted as a "single" member (like the Witches 5 from ''Franchise/SailorMoon''--which was actually six girls, but two of them were twins). Particularly weird when they're HalfIdenticalTwins.

A subtrope of TheDividual. Compare ThoseTwoGuys. Often overlaps with HeterosexualLifePartners.



[[folder:Anime & Manga]]
* The Hinagiri twins from ''Manga/AliceAndZoroku''. While they've grown out of it at the start of the series, a flashback shows that when they were taken to the institute, the only way they could tell ''each other'' apart was because they had different powers.
* [[CreepyTwins Hansel and Gretel]] from ''Manga/BlackLagoon''. Sure they are presented as slightly different personalities, with different genders, until they switch the gender and accompanying personality between them.
--> "I'll be Gretel for a while, now."
* Nene and Nono from ''Anime/BloodC'' [[spoiler: (although this is mostly just an act).]]
* The Tachibana twins, Masao and Kazuo, in ''Manga/CaptainTsubasa''. They're also GenreSavvy to the point of using their single-mindness as a game strategy.
* The Twin card from ''Manga/CardcaptorSakura''. They move in perfect symmetrical unison and can only be sealed after being beaten simultaneously, as they're pretty much just two halves of a single entity.
* ''Manga/ACentaursLife'' has single-minded ''triplets'' in Manami's little sisters Chigusa, Chinami and Chiho. It's to the point where they're often referred to collectively as "Chi-chan", as though they really were one person.
* In ''LightNovel/ACertainMagicalIndex'' this is portrayed both more literally than normal and more ''expansively'' than normal. There are just over ten thousand Misaka clones left out of an original twenty thousand and they're all referred to both as the Sisters and as the ''actual'' sisters of Misaka Mikoto. Though some characters view them as individuals, it would be more accurate to stay each one is a unique unit, all of which are an addition to the overall Misaka network. So in truth they really do all have one mind and they are constantly in mental contact, so when multiple Misakas are present they tend to finish each others sentences without hesitation.
* Literal case in ''Manga/{{Claymore}}'' with Alicia and Beth. They were trained/built that way too; the Organization hoped to create a warrior who could [[SuperpoweredEvilSide become]] [[AndThenJohnWasAZombie an]] [[EldritchAbomination Awakened Being]] and then come back, something requiring exceptional willpower - accordingly, they decided to design one twin to be the Awakened Being (Alicia) and one twin to be the willpower (Beth). They also weren't the first of the Organization's attempts at this or the last - after them, two trainee twins are seen (they don't last) and, before them, [[spoiler: Rafaela and the Abyssal One Luciela of the South, who were initially dramatic failures, but eventually ''do'' become SingleMindedTwins as The Destroyer.]]
* [[CreepyTwins Jasdero & Devit]] from ''Manga/DGrayMan''. Literally. They even do a fusion thing where they fight as 'Jasdevi;' it took a while to learn their individual names.
%%* Pyun and Potaro from ''Anime/DaiMahouTouge''.
%%* ''Anime/DarkerThanBlack'' has a pair of twins that are exactly the same.
* In the increasingly-weird later novels based on the ''VideoGame/{{Doom}}'' games, the main characters encounter a member of a species of aliens that look vaguely like upright-walking gorillas and are born as SingleMindedTwins. They choose the name, for ease of use of the humans, "Sears & Roebuck".
* Mairu and Kururi, [[spoiler: Izaya Orihara]]'s younger sisters in ''LightNovel/{{Durarara}}'' -- Though they outwardly act as PolarOppositeTwins. Playing with the trope a bit, the twins' single-mindedness is an indicator of how [[CuteAndPsycho unhinged]] and [[CreepyTwins detached from reality]] growing up with [[spoiler:Izaya]] has made them.
* Imari and Sayoka from ''LightNovel/{{Inukami}}'', two of Kaoru's Inukami, speak and act in unison.
%%* Emi and Yumi in ''Anime/IrresponsibleCaptainTylor''.
* Ai and Ren from ''LightNovel/{{Kanokon}}'', the poor ninja duo.
* In ''Manga/MagicalGirlLyricalNanohaVivid'', Dieci notes that the first time the twin Combat Cyborgs Otto and Deed have disagreed on anything is whether Corona or Rio will do better in the DSAA Inter-Middle Championship. This disagreement is presumably because the twins each trained one of the girls, and thus chose to favor the one they trained.
** Despite being more or less single-minded, they do have distinct differences, the most obvious part being their appearance. Otto is a {{Bifauxnen}} and {{Tomboy}} who works as a crossdressing female butler, while Deed looks and acts much more feminine and wears feminine clothes. Both were stoic and quiet before their HeelFaceTurn, but both mellowed out at the same degree, while retaining their polite personalities; and sometimes, they even wear (feminine) twin outfits. Another obvious difference between them is their Inherent Skill. Otto's Ray Storm shoots lasers, and Deed's Twin Blades is a pair of DualWielding {{Laser Blade}}s.
* Souya and Shirase from ''Anime/MawaruPenguindrum''.
* ''Manga/OsomatsuKun'' centers around single-minded ''sextuplets''; the six identical Matsuno brothers do have some individualized traits, but usually act and are treated as a single unit. This is averted in the 2015 revival series ''Anime/OsomatsuSan'', where the brothers have [[DivergentCharacterEvolution developed different personalities from one another]] and [[IdenticalTwinIDTag are easier to tell apart in appearance]].
* Houzuki and Bonbori from ''Manga/OtomeYoukaiZakuro''. They're good natured and see Hanakiri Ganryuu as a playtoy, but they are also half-spirit. Good idea not to mess with them.
* [[SubvertedTrope Subverted]] in ''Manga/OuranHighSchoolHostClub'' with identical twins [[{{Tsundere}} Hikaru]] and [[TheQuietOne Kaoru]]: they start out following this trope to a tee, speaking together and FinishingEachOthersSentences, but by the middle of the series they've developed entirely distinct personalities... and [[GenreSavvy Kaoru even recognizes that this trope is unhealthy]] and takes steps to try and avoid it.
** Even before that, it was established early on that Kaoru was passive while his brother was aggressive, both on and off their Host Club "stage." Later on it's revealed that they put on an imitation of this trope to drive people away outside of school. When Haruhi manages to see through this act, they start loosening up, to the point where their true personalities begin to surface.
** They're a little surprised by how many differences they actually have; they tended to think of themselves this way a lot of the time, especially after the only babysitter they ever liked turned out to be an infiltrator and reinforced their preference for distrusting everyone who wasn't them. Panic is had on Hikaru's side when he realizes there is a gap forming down the middle of their 'us.'
*** They did the 'falling in love with the same girl' thing, and their different reactions to the dilemma set off the division storyline. Basically, Kaoru is naturally more mature, and winds up taking care of Hikaru in this regard.
* ''Manga/RanmaOneHalf'' has two sets of Single Minded Twins; one unique to the anime, one to the manga. The anime has Ling-Ling & Lung-Lung, who aren't identical twins (with different hair colours, eye colours, weapons and hair styles), but nevertheless act as functionally one person. The manga has Pink & Link, who act like this when they come to Nerima, but are portrayed as being PolarOppositeTwins in their backstory.
** The first [[TheMovie movie]], ''Big Trouble in Nekonron, China'', has the Lucky Gods Daikokusei and Daihakusei, two Go-playing siblings who are functionally identical. The only difference between them is that one plays white and the other plays black.
* ''Franchise/SailorMoon'':
** Ptilol and Cyprine of the Witches 5, who were ''really'' one person in two bodies. In the French dub of the [[Anime/SailorMoon anime]], they refers as each other [[LiteralSplitPersonality ''doubles'']], and their names are Émilie and Émilia. Up until they can't agree on how to kill someone, anyway.
** There's also a pair of youma under Nephrite who have different powers--dark reflections of Mercury's and Mars'--but otherwise look nearly identical except for color and act as one until they have a spat (over which is doing more to kill the senshi) which gives the soldiers the in they need and the audience a ham-fisted sermon about cooperation.
** Despite so little screentime, in the [[Manga/SailorMoon manga]] Phobos/Deimos, Lethe/Mnemosyne, and Chi/Phi might be like this. Chi and Phi seem to be one-minded in wanting to kill the senshi, anyway.
* In ''Manga/{{Saiyuki}}'', Gonou seems to have believed this about himself and his HalfIdenticalTwin sister, which in his mind justified [[{{Twincest}} their relationship]]. Subverted in that they were canonically matching-but-opposite personalities, and it's presented as unhealthy.
* ''Anime/TheSecretGarden'': Dickon and Martha's youngest siblings in the anime series.
* The second season of ''LightNovel/{{Slayers}}'' has a pair of these; identical twin martial artists who want to be famous pop idols and who get into a fight over what Lina thinks is a book of spells, but turns out to be a collection of lost folk remedies. For added measure, Mimi and Nene are [[ShoutOut physically identical]] to Manga/RanmaOneHalf's Shampoo.
* Jougan and Barinbou, the twin [[TheBigGuy Big Guys]] from ''Anime/TengenToppaGurrenLagann''. They are never seen apart from each other, and while they don't finish each other's sentences, they often do split a complete statement between them, with one taking one full sentence and the other taking the next.
* ''Manga/TokyoGhoul'' has multiple examples of this in the series.
** Kuro and Shiro start out as this, mirroring each other in monochromatic clothing as suits their names. Then [[spoiler: Shiro is killed, forcing Kuro to develop into her own character as an AngstySurvivingTwin]].
** Gagi and Guge, twin {{Mooks}} that accompany Naki as his bodyguards.
** While never explicitly stated to be twins, the Bin Brothers function as a single character and never show their faces. After their death, their [[TailSlap kagune]] are combined together to repair [[DropTheHammer Dojima]].
%%* The Autobot Clones and Decepticon Clones in ''Anime/TransformersHeadmasters''.
* In the anime version of ''Manga/{{Trigun}}'' this trope is referenced by the young Knives: once positively, with regard to one of them being bullied, and once negatively, after he gives himself a haircut: "if we stay the same, we won't have any individuality."
** Of course, they then spend over a century as PolarOppositeTwins.
* Mei and Kyū (Para and Dox in the dub) in ''Anime/YuGiOh''. They had [[NoNameGiven NAMES?!]]
* ''Anime/YuriOnIce'' has the Nishigori triplets, who all share the same mischievous, figure skating-obsessed personality between the three of them. They'll also [[SpeakInUnison speak in unison]] or [[FinishingEachOthersSentences finish each other's sentences]] fairly often.

* ''Radio/BobAndRay'' had a pair of recurring characters named Clyde and Claude [=McBeeBee=], non-identical twin bandleaders who went everywhere together and always spoke in unison.
* One comedienne specifically cites and mocks this trope. "I have a twin brother. People are always asking me things like, 'You're twins; can you hear each other's thoughts an' stuff?' 'Yeah. Oh, hang on...he thinks you're an idiot.' "

[[folder:Comic Books]]
* Ladyhawk, a supporting character(s) in ''ComicBook/SpiderGirl'', is/are a set of twins sharing the same superhero name and identity (so they can operate at full-time for a single hero while still maintaining private lives). They are implied to have distinct personalities, but since their screen-time is so limited, the only observable difference is that one of them is more experienced.
** Now that [[spoiler: one of them has been forced to retire after being injured by the Hobgoblin]], they seem to have developed more of a SiblingYinYang.
* The Stepford Cuckoos (Celeste, Esme, Mindee, Phoebe, and Sophie) in the ''ComicBook/XMen'' family of books, are identical quintuplets and form a "Five-in-One" telepathic mind. [[spoiler: Later events show the "hive" mind splintering, leading to the deaths of Esme and Sophie.]] Much later in ''ComicBook/UncannyXMen'', Celeste dyes her hair and starts dressing differently from the others (who are pretty upset about it). And then Mindee dyes ''her'' hair. They still all act alike, though.
* In ''[[Comicbook/RobinSeries Robin Year One]]'', [[ComicBook/TwoFace Two-Face]] employs a pair of these, identical suits and finishing each other's sentences included. Given Two-Face's [[TwoFaced gimmick]] it's peculiar that he doesn't have them more often.
* Though never explicitly stated (it's implied to be the result of a string of freak coincidences), Franchise/{{Batman}} villains the Trigger twins. They first met when they both attempted to rob the same bank, only to discover their exact resemblance to one another. Ever since, neither of them has ever seemed to come up with an idea the other hadn't been thinking of as well.
* ''ComicBook/LaRibambelle'': Atchi and Atcha are two young Japanese twin brothers, who often talk and move in unison.
* ''ComicBook/{{Jommeke}}'': Annemieke and Rozemieke, who are young twin girls who are basically the same characters and also look the same.
* ''Franchise/{{Tintin}}'':
** A strange example are Thompson and Thomson who, apart from their moustaches, look exactly like twins. They dress, act and move the same and often finish each others' sentences. They also appear to live in the same house and even in the same bed! Still the linguistic difference in the spelling of their name suggest they are not related to each other at all. Furthermore, in the original French, they were known as Dupont & Dupond, which are even ''pronounced'' identically -- this was kept up at least to some extent in most translations, including English, where they are known as Thompson and Thomson.
* ''ComicBook/SuskeEnWiske'': In [[spoiler: "De Schat van Beersel"]] an identical looking triplet plays an important role.
* Ken & Kyle Katayanagi, the 5 and 6 evil exes of Ramona, from ''ComicBook/ScottPilgrim''. While we can't see much of them through volume 5, as they usually send robots to attack Scott, they pretty much seem to think and talk at the same range, finishing each others sentences at times.
* ''ComicBook/{{Superlopez}}'': [[ZigZaggingTrope Zig-zagged]] with Jaime's cousins Adolf and Rodolf from ''Al centro de la tierra''. They really are able to think as one, but if one of them somehow makes the other angry, a fight between them is sure to break out.
* Ayla and Nias of ''ComicBook/RedSonja'' share every frame and complete each other's sentiments if not sentences. They also never speak to each other - apparently it's unnecessary.

[[folder:Fan Works]]
* An author going by "persian85033" has produced an ''WesternAnimation/XMenEvolution'' [[http://www.fanfiction.net/s/2024204/1/ fanfic]] involving, may God help us, the Single Minded ''Dectuplets'' Maria Xoaquina, Maria Xitlalli, Maria Xaviera, Maria Xacinta, Maria Ximena, Maria Xiomara, Maria Xochilt, Maria Xosefina, Maria Xulia, and Maria Xamila, who literally refuse to be separated even for the length of a single school period: the entire school has to be rearranged so that they can be in the same room for every class.
* In ''Fanfic/HarryPotterAndTheMethodsOfRationality'' it's stated that Fred and George have almost identical thoughts if they're given the same information. They only talk to each other to share something the other doesn't know about and on the very rare occasions that they disagree with each other they feel like something has gone deeply wrong. Apparently this is normal for magical identical twins and in times past families would actually [[DeliberateValuesDissonance kill one of the twins at birth.]]
* In ErrorOfSoul, another ''Franchise/HarryPotter'' FanFic, Fred and George are [[spoiler:continuously synchronised, so they're unable to remember who is who from day to day.]] The central concept of the plot is this gradually happening to *Harry and Hermione*, a situation that normally ends with the unfortunate soul-bonded pair trying to reach opposite sides of the planet.
* ''Fanfic/{{Equestrylvania}}'' has a slight variation (single-minded ''triplets'') in [[ThemeNaming Ear, Nose, and Throat]], the directors of the Ponyville Hospital. They constantly [[FinishingEachOthersSentences finish each other sentences]] and occasionally speak in unison. The one time they don't do either is when Throat asks his brothers whether they think he [[ShipTease has a shot at Twilight.]]
* Dyno and Mite from ''Fanfic/MyLittleUnicorn''.
* ''FanFic/{{Sight}}'' Jushirou Ukitake's zanpakuto, Sougyo no Kotowari are indistuighable in both appearance and personality and often SpeakInUnison. Ichigo is recommended to refer to the both of them as Sougyo no Kotowari.
* In the ''WesternAnimation/CodeLyoko'' fanfic ''[[https://www.fanfiction.net/s/2680689/1/Lyoko-Championship Lyoko Championship]]'' and in its sequels Dean Peccadillo aka Shadow of Team Sin uses this as his ability in the game. His special power allows him to create two clones of himself which move and speak perfectly in-sync with each other. Odd has commented multiple times that this act really creeps him out.
* The "Reverse Pines" DarkFic [=AU=] of ''WesternAnimation/GravityFalls'' transforms the normally adorable Dipper and Mabel into this. They became a frightening pair of psychic HalfIdenticalTwins with IcyBlueEyes who [[TroublingUnchildlikeBehavior murder and engage in the occult]]. The only real difference in their psychopathic personalities is Mabel's rather yandere tendencies.
* ''FanFic/BlackSky'' brutally deconstructs it with Fred and George Weasley: their family's unability to differentiate the twins is presented as heavy neglect hinting the Weasleys don't care about them as persons rather than a single entity. When Fred suffers petrification, George suffers a heavy trauma since he can't function by himself, something Dorea Black immediately decides to correct by pushing him to become an individual with his own friends and interests. When Fred is cured, he's very much displeased about George growing away from him and needs adjustement.

* ''Film/TheCorsicanBrothers'', as portrayed by Cheech and Chong. (Also, originally, as portrayed by Douglas Fairbanks, Jr. (1941), which Cheech and Chong were riffing off.)
* In ''Film/ThePrestige'', [[spoiler:"Borden" is actually a pair of twins who have spent their whole life letting everyone else think they are a single person; whenever they appear together in public, one is heavily disguised, and they switch roles as necessary. The only flaw in the plan is that they fall in love with different women.]]
* The Twins from ''Film/TheMatrixReloaded'', probably justified seeing as how they are computer programs.
--> ''Twin #1: We are getting aggravated.''
--> ''Twin #2: Yes, we are.''
* Don't forget Fanty and Mingo from ''Film/{{Serenity}}''.
-->'''Fanty:''' Domestic troubles?
-->'''Mingo:''' Domestic troubles?
** Although it's entirely possible they're doing this deliberately to mess with Mal.
* Numbers 3 & 4 from the movie ''WesternAnimation/{{Nine}}'', both of which are very skittish, are very curious about the world, and never (audibly) talk outside of their own [[FictionAry eye-flashing language]].
** They also have projector eyes, or at least one of them does.
* Skids and Mudflap from the ''Film/TransformersRevengeOfTheFallen'', both portrayed as rednecks trying to be gangstas. Skids, however, is somewhat more aggressive and intelligent then his brother (and also has a slight case of hero-worship for Optimus Prime), even though Mudflap is probably the better fighter and driver.
* The siamese twins from Film/TheCityOfLostChildren together called the "octopus".
* In ''Film/DudeWheresMyCar'', the twins that the heroes are dating spend all their screen time talking quickly and alternating with each other, and occasionally say the same thing in unison. An odd example as the actresses who play them, while they share a certain vague resemblance, are ''not'' identical twins or even related.
* ''Film/TheAdventuresOfPlutoNash''. A friend of Nash has his perfect wife cloned. They not only look the same, they SpeakInUnison too.
* As mentioned under "Literature", the ''Film/HarryPotter'' films play this trope straight with [[AlliterativeName Padma and Parvati Patil]], though the books [[AvertedTrope do not]]. Notably, the twins both seem to be Gryffindors in the films (as they're seen together in the Gryffindor common room in the ''[[Film/HarryPotterAndTheGobletOfFire Goblet of Fire]]'' movie), though Padma is a Ravenclaw in the books.
* Tío Oscar and Tío Felipe from ''WesternAnimation/{{Coco}}'' are never seen without each other or in non-matching outfits. Even their pictures on the Rivera family's ''ofrenda'' maintain the trend.

* ''Literature/HarryPotter'':
** Fred and George Weasley, at least superficially. They often finish each other's sentences and jokes. Rowling specifically envisioned slightly different personalities to the twins. Fred is braver and more outgoing and is the "leader," while George is more clever but meeker. For example, Fred is the one who initiates just about every hi-jinks they ever pull, and the one Ron complains about the most. The difference is very subtle due to their limited screen time, and their enjoyment of using this trope on their mother. To her credit, many found it surprising that [[spoiler:Fred was the one who died, stating that George's personality made him the more obvious victim.]]
** Notably averted with [[AlliterativeName Padma and Parvati Patil]]. Though they're identical twins, they have distinct enough personalities that they're sorted into two different Houses (Parvati in Gryffindor, Padma in Ravenclaw), and they spend enough time apart that Padma is hardly ever seen until [[Literature/HarryPotterAndTheGobletOfFire the fourth book]]; for most of the series, [[ThoseTwoGuys Parvati is far more likely to be seen with her best friend Lavender Brown]]. Played straight in the movies, however, where both of the twins appear to be Gryffindors, they're constantly seen together, and Lavender and Parvati aren't shown to be exceptionally close.
%% Don't bring up George marrying Angelina. As far as we know, she and Fred only went on one date.
* Sam and Eric from ''Literature/{{Lord of the Flies}}''. Throughout the book, their names evolve from "Sam and Eric" to "Sam 'n' Eric" and, finally, "Samneric", cementing them as one person. The only time they talk independently is after their camp is raided showing how effed up everything is getting. Even their description supports this idea - their skin looks stretched tight across their bones, [[{{Squick}} as if they don't have enough skin between them]].
* The ''Literature/{{Duumvirate}}'' actively tries to fulfill this trope. Telling them apart is considered a major challenge even for their close friends.
* In the Spider Robinson book ''[[Literature/CallahansCrosstimeSaloon Lady Slings the Booze]]'', Arethusa is literally a pair of single minded twins, two women who from birth were telepathic with each other to a constant degree, combined with some weird superstition in their parents, caused them to grow up as a single person in two bodies.
* The Twins from ''[[Literature/InheritanceCycle Eragon]]''. They don't even have names. Ajihad says to Eragon "I would tell you their names, but they have none." They act pretty much the same, looking alike, acting alike, and having the same loyalties.
* In another rare use of the 'One person, Two bodies' ploy, Miss Level, a village witch first met in Terry Pratchett's ''Discworld/AHatFullOfSky'' (''Literature/{{Discworld}}''), was born with two bodies, and people assumed her to be a set of twins, "then they thought [she] was evil." She lives a very prosaic existence for someone with two bodies. She meets an unusual end: [[spoiler: when only one of her bodies is killed, she survives, though is weakened from the blow, and eventually finds that she still remembers how to use two bodies, and thus, being a witch, gains basically telekinetic abilities.]]
* Creator/UrsulaKLeGuin's short story "Nine Lives" featured 10 clones who were essentially one being. [[spoiler:When nine of them died in an accident, the survivor considered himself "nine-tenths dead" and nearly lost his will to live.]]
* Creator/IanMcDonald's ''Desolation Road'' (set in the far future) had an incident with two clone-assassins, [=AlphaJohn=] and [=BetaJohn=]. They were two clones who were one being, with perfect telepathic connection, having the advantages of sharing all their senses. The victim realizes that [[spoiler:he can shoot one of them, and they'll both die]]. So he does that.
* In the ''Literature/OldKingdom'' trilogy by Creator/GarthNix, there are the twins of the Clayr, Sanar and Ryelle. They speak in synchronization and it is noted that their souls are bound around each other too tightly for even magic to treat them as separate beings. Though they do have some different traits; Ryelle is a better paperwing flier.
* Used on two separate occasions by David Eddings:
** In ''Literature/TheBelgariad'', Beltira and Beltika are like this ''before'' they become immortal sorcerors, and have both telepathy and millennia to become even more familiar with each other's habits and thought patterns. It's even effectively weaponised at one point, when Belgarath realises that their ability means they can cross-correlate two sets of prophecies (one detailed but utterly random, one sparse but in chronological order) to find the similarities and make a comprehensive whole.
** In ''Regina's Song'' the title character and her sister Regata are this, until the latter is raped and murdered, where they effectively become single-minded twins in a single body. Kind of. It's complicated.
* Used in some form in ''A Breath Of Snow And Ashes'' in the Outlander series, with Jo and Kezzie. [[spoiler:Namely, in that they end up [[TwinThreesomeFantasy mutually devoted--and married to--the same woman]], and there's a bit of a kerfluffle over whether it's "really" bigamy or not, if twins can be taken as the same soul shared between two bodies.]] Yeah. It's a bit weird.
* In ''Whispers'', by Creator/DeanKoontz, the heroine was almost raped and killed by a famous man before killing him herself. He couldn't have done it because he was away. As you can guess, it was his twin. The other comes back and talks about how she killed him. Turns out [[spoiler:their mother was impregnated by [[ParentalIncest her father]] and gave birth to twins. After some time, the stress drove her insane and she believed they'd been conceived when a demon raped her. To conceal them, she forced them to be one person, and locked them in a cellar with hundreds of horrifying, huge cockroaches that would crawl all over them when they didn't act or think as one. As a bonus, she made them believe they had demonic penises, and that they always had to hide them from everyone else. Now that they don't have [[{{Twincest}} each other]], their only "outlet" is with the only other person who knows--Mom. She's dead--but he thinks she's coming back as different women. [[{{Squick}} Shudder.]]]]
* Mark Frost's ''The List Of 7'' has Larry and Barry, identical twins and professional thieves. No one knew that they were indeed twins, so they posed as the same person. One of the brothers would appear in a pub or restaurant making a big show (one of the brothers liked to sing while the other liked to recite ribald limericks) while the other brother went to work cleaning out someone's flat. If one of the brothers was suspected, he could produce any number of witnesses to give him an alibi. When one of the brothers received a scar from a bullet wound, both brothers grew beards to cover the scar and maintain the fiction that they were the same person. Ultimately they were found out by Agent to the Crown Jack Sparks who pressed them into his service in exchange for a pardon for their crimes.
* ''Literature/WickedLovely'': Ani and Tish act like this, but in reality Tish is almost three years older, they have different mothers, and Ani is almost a full faerie whereas Tish is practically mortal.
* Ritva and Mary Havel of the Literature/{{Emberverse}} begin very much like this, but in the course of the second trilogy they show/develop somewhat more distinct personalities.
* Estha and Rahel from ''Literature/TheGodOfSmallThings,'' and this is PlayedForDrama, as they are frequently described as one soul split in two, and even describe themselves as "we" in the ''singular.''
* Creator/RobertAHeinlein:
** In ''Literature/TimeEnoughForLove'', [[ThemeTwinNaming Lapis Lazuli Long and Lorelei Lee Long]], Laz and Lor for short. Their case is made even more interesting by the fact they aren't "natural" twins, but rather twin {{Opposite Sex Clone}}s of protagonist Lazarus Long. The story plays their single-mindedness for humor, but they themselves are quite serious about it, claiming to possess TwinTelepathy and apparently ''practicing'' speaking in sync with one aother, because they enjoy messing with people's minds.
** Castor and Pollux in ''Literature/TheRollingStones'' fit this trope as well Laz and Lor do, and exhibit similar twin behaviours.
* In ''Literature/TheVampireFiles'' series, the Ruzzo brothers look and act so much alike, and work together so closely, that their fellow gangsters refer to them in the singular as well as the plural (e.g. "Tell Ruzzo to get their butt(s) in the car, already.").
* Flora and Fauna, Peter and Fudge's second cousins in the Judy Blume book ''Double Fudge''. The girls dress alike and sing together. To make things worse, the girls ''finish each other's sentences''.
* Eustace and Claude from the ''Literature/JeevesAndWooster'' series. At one point, when they're supposed to be heading to South Africa, they both independently fall for the same girl and independently leave the liner before it departs. They're then shocked to find each other when they both go back to Bertie's flat.
* Cersei and Jaime Lannister from ''Literature/ASongOfIceAndFire'' think of themselves this way -- Jaime is convinced that "If I were a woman, I would be Cersei," and Cersei says she only feels whole [[{{Twincest}} during sex with Jaime]]. Their POV chapters, however, reveal that they're wrong about this.
* The Gowder twins in ''The Stranger House'' don't fulfil the 'never apart' part of this trope, but they are not only indistinguishable but treated as entirely interchangeable by the other characters. They are known as Laal and Girt:[[note]]meaning little and big[[/note]] whichever twin you are talking to is Laal, and you never meet Girt (presumably when they're both present Laal is whichever you are addressing at that moment). No-one knows what the twins think about this. They're... odd.
* [[http://www.gutenberg.org/catalog/world/readfile?fk_files=1536195&pageno=2 Anything You Can Do...]] has a rather... scary yet different subversion. When Mart is two, his father brings him to work, '[[TemptingFate just stopping by]]'. A bad accident kills the father, leaving most of Mart's nervous system[[note]]everything but most brain and some spinal function[[/note]] severely damaged. The doctor recommends multilevel therapy, but the mother doesn't follow through. [[spoiler:Mart shares a psychic link with his twin Bart. Mart's condition means ''their minds can't balance out;'' Mart does not have the wealth of experience needed. Over the years, Bart's mind essentially ''copies over'' to Mart's.]]
* The ''Literature/AgeOfFire'' series has [=SiHezethant=] and Regalia, rare dragon twins born from the same egg, who are constantly commented on being so similar in appearance and mind.
* In the ''Literature/GentlemanBastard'' series, Calo and Galdo Sanza are essentially the same person. They usually work together, have the same skills and [[FinishingEachOthersSentences finish each other's sentences]]. Flashback chapters reveal that in their teens they they squabbled and adopted opposite appearances to distinguish their self-identities, but this was obviously a phase.

[[folder:Live Action TV]]
* Subverted on ''Series/OdysseyFive'', Kelsey and Bodanis, two of Neal's computer {{Geek}} friends are twins who are very similiar, but when the VerySpecialEpisode about [[AIIsACrapshoot evil AI]] [[{{Brainwashed}} mindcontrol drugs]] came around, Kelsey was hit and Bodanis asked Neal for help.
* In ''Series/GirlMeetsWorld'', Maya and Riley are intentionally created to be this show's Shawn and Cory. On the first episode guest starring Rider Strong (Shawn), this conversation takes place:
-->'''Maya''': Riley and I are the best friends on this planet.
-->'''Shawn''': Well, that's cute, 'cause Cory and I are the best friends in all of existence, which includes your crummy little planet. Cory and I finish each other's...
-->'''Cory''': Sentences!
-->'''Riley''': Yeah? That all you do? Because Maya and I can read each other's minds. Ready? What am I thinking of? One, two, three!
-->'''Both''': Pizza! One, two, three, clouds! One, two, three, Farkle!
* In ''Series/{{Quark}}'', there are the Bettys (played by a pair of Doublemint gum twins) who can't decide which one is the clone (answer: the pretty one) and often talk in unison.
* Corey and Trevor in ''Series/TrailerParkBoys'' are a non-related example.
* ''Series/MahouSentaiMagiranger's'' Nightmare Sisters aren't even identical, but almost all of Mea's lines amount to repeating the last one or two words of whatever Nai just said. (Of course, they're both halves of a vampire queen who split herself because she got lonely.)
** [[ScrewYourself Must... not... make... joke...]]
* ''Series/PowerRangersRPM'' has Gem and Gemma, who don't appear to be capable of independent thought (or speech; the page quote is probably the only time they aren't written as if only one person was talking, with Gem delivering the first half of the sentence and then Gemma taking over for the second half). For all intents and purposes, they are one person in two bodies. No explanation is made of this. In fact, it's not even commented upon.
** At least, not initially. Six episodes after their first appearance, they finally begin to be split up (though usually not by their own choice) and are given individual plot threads and slow-going characterization. However, it's doubtful they'll ever lose the singleminded-ness, except on the rare occasions they disagree on something (when they do disagree, it's generally about romance, with Gem being overprotective of Gemma).
* Double Trouble, a duo of recurrent villains in ''Series/WhereInTheWorldIsCarmenSandiego''. Their description reads: "Two guys, one mind, no shame".
* Averted in ''Series/StarTrekVoyager''. When the oft-mentioned but rarely-seen Delaney twins from Steller Cartography finally make an appearance, one of them is attracted to Harry Kim, much to his annoyance as Harry prefers her sister. When a nonplussed Tom Paris points out that it shouldn't make any difference, Harry proceeds to list a number of character differences between the two, ending with "that cute dimple on her right cheek." In their one appearance, while playing twin henchwomen of Dr. Chaotica in the [[ShowWithinAShow Captain Proton holonovel]], they act distinctly different, one more assertive than the other.
* ''Series/{{Battlestar Galactica|2003}}'': The horde of Number Eights that confront Boomer in "Kobol's Last Gleaming" finish each other's sentences to creepy effect. Averted with Boomer herself, and Athena and a handful of other Eights that stand out. Averted by the Sixes constantly but played straight by the other models constantly.
** It's eventually revealed that disagreements are settled by each of the twelve models voting as one, and Boomer causes quite a stir when she votes against all the other Eights, tipping a crucial tied vote between the models.
* ''Series/SeventhHeaven'' with Sam and David. One wonders if the show runner has ever met real life twins.
* The series ''Series/PicketFences'' had deputy Kenny briefly date a pair of SeparatedAtBirth twin sisters whose bond was so strong it drew them together. In their first appearance, one sister had to pull her car over to orgasm while the other sister was having sex -- and this was before they even met! After they do meet, they insist on dating Kenny jointly.
* The Cousins in ''Series/BreakingBad'', reinforced by the fact that they barely speak.
* Invoked and played with in Season Four of ''Series/ArrestedDevelopment''. George-Michael unintentionally offends a pair of twins by assuming they will vote the same way over a roommate/housing issue. As a result, they make a point of voting for opposite sides, leading to a tie (which remains unbroken as, rather than bring in a single tie-breaker, the two brothers insist on bringing in more and more ''pairs'' from their "Twin Club" to vote/demonstrate-how-they-avert-this-trope). To top it off, all the twins are either dressed identically or matching their sibling, and their behavior and dialogue throughout the scenes totally follow the trope even as they loudly protest its inaccuracy.
* ''Series/JoanOfArcadia'': Literal. At one point, God appears to Joan as a pair of twin girls. This being God, he/she/they have no problem speaking as one voice despite having two bodies.
-->'''Joan''': I thought we were going with ''mono''theism.\\
'''God Girls''': I'm impressed you know what that is.


* In his book ''I Am a Strange Loop'', philosopher-scientist Douglas Hofstadter describes an AlternateUniverse called "Twinwirld", in which (almost) everyone is a pair of Single Minded Twins, called a "pairson". (Single births are called "halflings" and considered unbelievably pitiful.) This is an analogy for the two hemispheres of the brain.

[[folder:Tabletop Games]]
* Alpharius and Omegon from ''TabletopGame/{{Warhammer 40000}}'' are described as "two bodies with a single soul". They're so similar they often exchange parts they play and pretend to be each other when "Alpharius Omegon" needs to be in two places at a time.
** And their ''entire legion'' looks identical to him/them, [[IAmSpartacus so no one can single out their Primarch for assassination.]]
* ''TabletopGame/DungeonsAndDragons'' featured a race called the Dvati who were based on this trope. Each "individual" Dvati was a pair of empathically linked identical twins. They literally only have one soul(and by extension one set of hitpoints, divided evenly) between two bodies.
* Kat Brokensoul, from the ''TabletopGame/WerewolfTheForsaken'' ''Night Horrors'' book, is actually two werewolves operating almost seamlessly as one person. In fact, their father specifically orchestrated it so that, legally, only one of them existed for... some reason. They even have a rite that lets them swap scents and employ a limited sort of TwinTelepathy, which didn't help their becoming TheDividual.
* Depending on how the GM runs the game, clones in ''TabletopGame/{{Paranoia}}'' often end up like this. This is typically enforced by encouraging players to treat a new clone as a "new life" continuation of the previous one, with the same skills and knowledge of the predecessor. In-game, it's usually justified by saying the standby clones are watching the actions of their active sibling through monitoring rooms during a mission.

* [[SubvertedTrope Subverted]] in the stageplay version of ''PeterPan''. Two of the Lost Boys are twins, but Peter had never seen twins before they showed up and wasn't sure what to do with them. By the time the book begins they are simply each called "Twin" and are treated as one person. One is never without the other and they finish each other's sentences. Lampshaded when only one has a dream and the other says not to tell Peter because they 'didn't think they ought to have different dreams'.

[[folder:Video Games]]
* Timmy and Tommy Nook from ''VideoGame/AnimalCrossing'', who both say the same lines, with little gray words at the end representing the other one saying it at the same time.
* Ami and Mami from ''VideoGame/TheIdolmaster''.
** Now subverted with Idolm@ster 2 and by extension the new anime since Mami has grown her hair out and they no longer try to pretend to be the same person on stage.
* Zorn and Thorn, from ''VideoGame/FinalFantasyIX''. They habitually repeat what the other says (i.e. "what the other says they habitually repeat"), and their boss reveals they aren't even really two beings just before they merge into a single two-headed EldritchHorror body for their final boss fight.
** Franchise/FinalFantasy series in general averted this.
*** [[VideoGame/FinalFantasyIV Palom and Porom]] is the first prime example. Palom is boastful and rude, Porom reserved and polite.
*** In ''VideoGame/FinalFantasyVI'', Edgar is a ChivalrousPervert while Sabin is chaste, but acts without thinking.
*** For [[VideoGame/FinalFantasyXII Basch and Gabranth/Noah]] it's quite complicated, as their different personality might be due to different "environment" they faced.
*** In ''VideoGame/FinalFantasyXIV'' Alphinaud and Alisaie, despite being HalfIdenticalTwins in terms of their looks. While Alphinaud throws himself into the task of filling the shoes of their grandfather, Archon Louisoix, and assisting the Scions of the Seventh Dawn in repelling the Garlean threat and restoring stability to Eorzea, Alisaie grows disgusted with Eorzea's politics and follows her own path, seeking the truth behind the Battle of Carteneau and Archon Louisoix's disappearance and ultimately finding the Dreadwyrm Bahamut on the verge of resurrection. Alisaie is largely absent from the main story while Alphinaud remains a central figure throughout; this status quo changes towards the end of the Heavensward expansion, where Alisaie returns with a new costume, new abilities, and new purpose.
* In the backstory for ''VideoGame/{{Xenogears}}'' (as revealed in the games [[AllThereInTheManual Perfect Works]] book) [[spoiler:Miang's incarnation during the Zeboim era is as a set of identical twins, making this another example of the "one person two bodies" variant]]
* An odd variation is taken in ''VideoGame/RuneFactory2''. Sera and Serina are twins who [[InformedAttribute you are told are very different]] because [[TomboyAndGirlyGirl one is "bookish", while the other is "sporty"]]. In actual fact, however, they are separated in only one quest, where one begs you to reunite her with the other, at that, and not only like doing the same things, but count as one person in your menu, and giving items to one counts as giving it to the other. As a second-generation romantic option, [[OT3 dating one means dating the other]], and they even complete (or simply repeat and enunciate upon) each other's sentences. Thanks to a probably-unintentional bug, they're even available as [[BiTheWay romantic interests]] to a female PC.
* Ashley and Sidney Webber of ''VideoGame/BackyardSports'' are like this. Achmed and Amir Khan have similar personalities, but have opposite abilities.
* Koume and Kotome from ''VideoGame/TheLegendOfZeldaOcarinaOfTime''. Despite representing two opposing forces of nature, they literally combine to create the most disturbing porn star ever.
* In the Loose Canon comic of ''VideoGame/TeamFortress2'', Redmond and Blutarch Mann are this, [[CainAndAbel much to their disgust]].
* Gwendolyn and Charlotte, the twin daughters of Rose Somerset from the ''Ravenhearst'' [[VideoGame/MysteryCaseFiles game series]], are a CreepyTwins example, speaking in synch with one another and dressing identically. It's downright shocking to see them separated, even temporarily, in ''Escape From Ravenhearst''. Possibly an '''enforced''' example, as the girls spent most of their brief lives and unhappy existence as ghosts being browbeaten by Charles Dalimar, who ''wanted'' his stolen "family" to conform to his notion of doll-like, carbon-copy perfection.
* [[Videogame/BioshockInfinite The Lutece Twins]] finish each other sentences, always travel together and are rarely seen far apart. [[SubvertedTrope Subverted]] both in that [[spoiler: they are actually two versions of the same person from different dimensions partly merged after a TeleporterAccident]], and in that while they fulfill this trope, they do have subtle distinctions in personality, Rosalind playing a [[TheCynic sardonic]] [[RedOniBlueOni red oni]] to Robert's [[TheAntiNihilist snarkily optimistic]] blue oni.

[[folder:Web Comics]]
* In ''Webcomic/SchlockMercenary'', T'Chukk is from a race of bicameral lifeforms; he's a single being in two bodies, synced by radio. A bit of hyperspace communications augmentation, and he's able to be his own wingman in the crew's fighter craft wing.
* Gemini Gold/Silver in ''Webcomic/TriquetraCats''.
* In ''Linburger,'' Firne are a single person in two identical twin bodies that change their sex organs with the phases of the moon (but always have boobs).
* Zig-zagged in ''Webcomic/GrrlPower''. Harem has the ability to [[MesACrowd create up to five duplicates of herself]], and they all share one consciousness. But Harem has ''personalized'' each one, with different hairstyles, tattoos, piercings, wardrobes. The cast page specifically states that for each different body, she affects different personalities, but it's largely a farce. In the "Dabbler's Science Corner" comic, she specifically states that there's no "this one" or "that one" for her bodies, there's just her. In summary, Harem is one person that has the potential to create a Single Minded Quintuplets situation, but goes out of her way to not do so.
* In ''Webcomic/AliceAndTheNightmare'', the Vena twins seem to be this. They often speak together, express the same emotions and finish each other's sentences.

[[folder:Web Original]]
* Hamburger Pattie of the ''Roleplay/LeagueOfIntergalacticCosmicChampions'' could split into two and become a Double Pattie.
* ''Void Dogs'' has Nick Bradley, clone lifer (a subculture that emulates this trope through a mix of cloning and memory merging).
* The popular Website/YouTube video "[[http://www.youtube.com/watch?v=wCF3ywukQYA&feature=rec-HM-r2 Shoes]]" references this when the mother of a pair of twins asks "Don't they have the same thoughts?" Nothing could be further from the truth.
* Parodied in ''WebAnimation/GirlchanInParadise'', when two twin girls finish each other's sentences, are called "annoying" for it, then finally, are shot dead.
* [[http://www.scp-wiki.net/scp-284 SCP-284, The Twins]], from the ''Wiki/SCPFoundation'' are ''literally'' Single-Minded Twins, in the sense that they both [[HiveMind share a single brain]] between them, any [[TwinTelepathy thoughts]] or sensations experienced by one is also experienced by the other.
* The twin sisters of the Baron Richmond, in ''Literature/{{Twig}}'', are referred to only as "the Twins" and act with the same amount of casual sadism, being identical and interchangeable. The same applies for their twin younger sisters who [[BodyHorror live inside of them]].

[[folder:Western Animation]]
%%* Ian and Jeremy from ''WesternAnimation/BarbieAndTheDiamondCastle''.
* In ''WesternAnimation/BatmanBeyondReturnOfTheJoker'', Dee-Dee/The Deeds/Delia & Deidre Dennis are twin sisters who may as well be two halves of one person. Besides looking and talking exactly the same (both twins are rapidly and amusingly voiced by Creator/MelissaJoanHart), they move and fight in incredibly effective teamwork. Just goes to show how devastating it would be if villains didn't [[MookChivalry attack the hero one at a time]]...
** In ''[[WesternAnimation/JusticeLeague Justice League Unlimited]]'' they return for an episode set in a time travel corrupted future where they're given the power to duplicate, making even more copies with the same single mind.
** They have been known to address one another as 'Dee Dee'; as in "You think so, Dee Dee?" "Oh yeah, Dee Dee."
* Twirly and Whirly from the ''WesternAnimation/BitsyBears'' pilot.
* The Interesting Twins From Beneath The Mountain in ''WesternAnimation/CodenameKidsNextDoor'' act this way when they're calm, but this is subverted whenever their plans (frequently) backfire on them. [[PolarOppositeTwins The female twin is shown to be easily angered and volatile while the male twin is calmer, submissive, and more sensible]], but becomes dominant and protective when his sister breaks down when pushed far enough.
* Creator/WaltDisney's Huey, Dewey and Louie, who were scripted, and treated, as one character in their earlier appearances. In the ComicBook/DisneyDucksComicUniverse, they're also often FinishingEachOthersSentences.
%%* Al and Moo Sleech from the Nicktoon ''WesternAnimation/{{Doug}}''.
%%* Charles and Mambo from ''WesternAnimation/{{Duckman}}''.
* Tad and Chad on ''WesternAnimation/TheFairlyOddparents'' are a variation. They aren't related, but other than different skin colors they could be twins.
* Tek and No from ''WesternAnimation/{{Foot 2 Rue}}'' are definitely this, usually being referred to by their portmanteau name the Teknos, and being completely identical. They start becoming a little more individual in season 3, but are still impossible to tell apart.
%%* Tomax and Xamot from ''Franchise/GIJoe''.
* Walter and Perry of ''WesternAnimation/HomeMovies'' aren't related, but they are never apart (and almost always holding hands). Their less-than-totally-innocent relationship makes them essentially one character.
* Notably averted in ''WesternAnimation/InvasionAmerica'', which had Sonya and Simon, a pair of psychically linked twins with super-powers which were stronger when they touched each other... and still gave them different personalities and independent character arcs.
* Jim and Tim from ''WesternAnimation/KimPossible''. They're basically the same person in two bodies.
** Also Wego; they even shared the same name. They have [[MesACrowd self-duplication]] as a superpower.
* Whittany and Brittany Biskit in ''WesternAnimation/LittlestPetShop2012'', who almost always agree with each other, and when in a musical sequence, always sing in unison unless complementing each other's lines. However, there have been a few moments when the two are separated, where it's shown that each of them is ''intentionally'' trying to act like the other one to avoid rejection from her.
* The Bully Brothers from ''WesternAnimation/ThePerilsOfPenelopePitstop''.
* Rumored to be the case with I and Am, a brother team of bounty hunters who appear in the ''WesternAnimation/SamuraiJack'' episode "The Princess and the Bounty Hunters". Whether this is true or not, the one of twins often finishes a sentence that the other starts (and they [[RhymesOnADime often rhyme their words]]) and as proven near the climax of the episode, they can communicate with each other telepathically.
* Sherri and Terri in ''WesternAnimation/TheSimpsons''.
** Marge's sisters, Patty and Selma, started out this way, but diverged from each other over the seasons. Selma craves companionship, having gotten married several times and eventually adopting a Chinese girl, while Patty was earlier described as not liking to be touched, and more recently came out as a lesbian.
* Hip and Hop from the Western ''WesternAnimation/SuperMarioBros'' cartoons, based loosely on the Iggy and Lemmy (who had no such relation) from the games ''[[SuperMarioBros Super Mario Brothers 3]]'' and ''[[SuperMarioBros Super Mario World]]''. ''Mario'' fandom is fond of the cartoon personalities of all the Koopalings, however, and so [[PatchworkFic uses this trope but the games' names]].
* ''WesternAnimation/{{Superjail}}'''s very own Twins fall under this trope most of the time they appear, and that's only one of the many strange parts to them.
* Más y Menos from ''WesternAnimation/TeenTitans''; they actually have to be touching to use their super-powers.
* Bill and Ben in ''WesternAnimation/ThomasTheTankEngine'' (and to a far lesser extent, Donald and Douglas, although they are more independent of each other).
** Skarloey and Rheneas. Both started out as young and hot-tempered but at 140 years old they have mellowed out quite a bit.
* Katie and Sadie from ''WesternAnimation/TotalDramaIsland'' are another case of unrelated friends who act almost exactly alike and are horrified at the thought of being separated. Interestingly, {{Fanon}} often tries to interpret or develop them to be more separate, while the show passed up a perfectly opportunity to do so (between Katie and Sadie's eliminations}.
* Jetfire and Jetstorm from ''WesternAnimation/TransformersAnimated''. It's made all the more literal after they are badly injured and implanted with Starscream's programming during an experiment in allowing Autobots to fly. Besides being able to turn into jets, they gain the ability to [[CombiningMecha combine]] into a single form known as Safeguard.
* [[HalfIdenticalTwins Phil and Lil]] from earlier seasons of [[http://tvtropes.org/pmwiki/pmwiki.php/WesternAnimation/Rugrats Rugrats]] were pretty much the same character, save for the occasional argument: Rambunctious, fun loving, and drawn to all things gross. In fact, the one time they ''tried'' to be different people, the episode ended with them deciding they were happier being like each other. Later writers decided to tone down Lil's tomboyishness and [[TomboyWithAGirlyStreak have her start referring to herself as "prettyful".]]
* ''WesternAnimation/BeCoolScoobyDoo'' has a set of these in one ep. They are about ten, and must finish eachother's sentences. Even if they are just saying "yes". Also played with when one disappears. The other can only start a sentence, but can not complete the thought.
* ''WesternAnimation/AdventureTime'' has the Flying Lettuce Brothers, old associates of Jake. Other than using a glove and a wirstwatch in different arms, they look and sound identical. Speaking in unision is part of their talent, as they only need to hear a single sentence and they can modulate their voice to sound exactly like the person who talked.
* The Twins in ''WesternAnimation/HowToTrainYourDragon'' and the SpinOff TV show ''WesternAnimation/DragonsRidersOfBerk'', not as much single-minded as other examples, but their personalities are so alike that they're generally treated as a single character. In their case is their PlayedForLaughs SociopathicHero behavior. Probably consequence that neither of them is very bright.

[[folder:Real Life]]
* An extreme example of such twins might be [[https://en.wikipedia.org/wiki/June_and_Jennifer_Gibbons Jennifer and June Gibbons]], aka the Silent Twins. They did this partly because Jennifer, ten minutes younger than June, felt she had to "catch up" so they would do everything as simultaneously as possible. Jennifer called all the shots on this, preventing June from any spontaneous impulse. They did everything they could to appear to be one mind in two bodies, and this plus the fact that they were black Caribbeans living in a 99% white small town in Wales caused them to be viewed as CreepyTwins by health care workers and hospital staff. Jennifer's death in 1993 literally released June to speak and live a normal life.
* In the UsefulNotes/NationalHockeyLeague, you have Daniel and Henrik Sedin of the Vancouver Canucks, who are known for being so in sync with each other that it's borderline supernatural. It became such commonplace to see them involved on each others' plays that Vancouver's local commentator has made a catchphrase out of "Henrik to Daniel... SCORES!"