History Main / SpotTheImposter

** The "[[KillUsBoth You'll have to shoot us both!]]" subversion gets [[DoubleSubversion double-subverted]] as well as heavily {{lampshade|Hanging}}d (even going so far as to call it a "trope") through lack of GenreBlindness on [[http://www.giantitp.com/comics/oots0397.html this page]]. Of course, this comic also shows that spotting the impostor is easy when he has [[SmallNameBigEgo an ego the size of the Tarrasque]].

* ''ComicBook/GoldDigger'' plays with this trope.

* In ''ComicBook/Supergirl2005'' ''Girl Power'' storyline, [[EvilTwin Dark Supergirl]] switches her costume with the original ComicBook/{{Supergirl}}’s at super-speed, in an attempt to fool Batman and Franchise/{{Superman}} as to who was the evil clone. Superman tries to spot the imposter by punching both girls, assuming -wrongly- that the real one will not retaliate. Finally, the real Kara gets fed up with the situation, and tells Franchise/WonderWoman to use her Lasso of Truth.
* An early Franchise/{{Batman}} serial strip had Batman disguise himself as a mob boss in order to free Robin -- unfortunately, the real one came back earlier than expected, ''and'' the boss' henchmen had recently decided to get rid of their BadBoss.

Typically, the situation will involve the impostor and the real person standing side-by-side, both claiming to be the real one, and the other heroes must use their wits to identify who is who, usually by finding a quality that the faker doesn't have (in comedic examples, a positive quality). Or the real person may ask that their friend [[KillUsBoth shoot both of them]] just to guarantee they get the imposter (and it's almost inevitable if the person has a [[HealingFactor super-healing power]]), which usually results in the heroes shooting the other one, because the impostor [[DirtyCoward wouldn't be noble enough]] to suggest making the HeroicSacrifice. This is often parodied these days where the imposter suggests it, knowing they'll assume the noble act to mark them out as the original — and sometimes double-parodied when this ends up outing the imposter since [[{{Jerkass}} the real person wouldn't be so noble]].

* On ''Website/MafiaScum'', many games of Mafia (a.k.a. ''TabletopGame/Werewolf1997'') use an [[https://wiki.mafiascum.net/index.php?title=Open_Setup open setup]] wherein everyone is told ahead of time how many of each role will be assigned. If a Mafia member and town member both claim to be the one town cop, the rest of town must determine who is the real cop!

Compare CoverIdentityAnomaly, ImposterForgotOneDetail (where the imposter's disguise has one subtle flaw), ImpostorExposingTest, and TwinTest (which may involve a person impersonating their identical sibling). See also: EvilTwin, BluffTheImpostor, ConfrontingYourImposter, TenLittleMurderVictims.

* ''VideoGame/LiveALive'' has the player stuck in the "Prove yourself" half of this in Cube's chapter. When faced with both Cube and a hostile robot modeled after him, Kato muses aloud that since the fake was only activated a short time ago, he couldn't have heard Kato's first idea for Cube's name (Koro or Rover, depending on your translation; either way, it's a cliché dog name). When you give the right answer, Kato yells for Darth to shoot the other one.

** The Howlers are rescuing French Resistance ally Frenchie from a prison. Halfway through the escape, Fury suddenly decks Frenchy then pulls off a fake mustache. The imposter gave himself away by referring to Howler Eric by name when Eric wasn't with the Howlers when they first met Frenchy.

* Spoofed during Chapter 7 in ''VideoGame/PaperMario64'', where several duplighosts ([[MeaningfulName ghosts that can duplicate your appearance and abilities]]) impersonate your partner. The first two encounters are played more-or-less straight, but in the third, the four duplighosts trying to duplicate Kooper the Koopa end up looking and talking like several different characters, including ''Luigi'', while [[BlatantLies still claiming to be Kooper]]. The one that impersonates Luigi even claims that you should trust him to be the real Kooper ''[[InsaneTrollLogic because you should trust your brother]]''.

* ''Fanfic/InfinityCrisis'': In ''Different Strokes'', when the Earth-51 Deathstroke attacks the team, Diggle and Thea assume it's their Slade. However, Oliver says the fighting style is different and how he took this guy down with a move Slade himself taught Oliver. Felicity then shows video of how this Deathstroke is a few inches taller than Slade and his voice pattern doesn't match either.

* ''VideoGame/LuigisMansion'' has a rather strange technicality here - [[spoiler:there are two versions of the King Boo & Bowser painting you can get at the end of the game: one in the US version which has King Boo and Bowser facing to the left of the painting, and the one in the PAL & Japanese versions which has King Boo & Bowser facing each other. The credits in ''Luigi's Mansion'' show that the US version of the painting is the real one, regardless of which version of the game you play. However, on the ''Luigi's Mansion'' racetrack in ''VideoGame/MarioKartDS'' & ''VideoGame/MarioKart7'', the mansion contains the PAL/Japanese version of the King Boo & Bowser painting. This makes it really hard to tell which version of the painting you get at the end of ''Luigi's Mansion'' is the real painting.]]

* ''ComicBook/{{Invasion}}'':
** ''ComicBook/WonderWoman1987'': Heading to rescue ComicBook/SteveTrevor from shapeshifting Durlans, Franchise/WonderWoman and ComicBook/CaptainAtom know who they're dealing with. When they're separated, each is approached by a Durlan posing as the other but see through it fast. In Diana's case, she asks "Atom" if Captain Nate Adam was with Trevor, the Durlan confirming it...not knowing Nate ''is'' Captain Atom. In Atom's case, he's able to quickly see that "Diana's" lasso isn't glowing.

* ''VideoGame/LuigisMansion'' has a rather strange technicality here - there are two versions of the King Boo & Bowser painting you can get at the end of the game: one in the US version which has King Boo and Bowser facing to the left of the painting, and the one in the PAL & Japanese versions which has King Boo & Bowser facing each other. The credits in ''Luigi's Mansion'' show that the US version of the painting is the real one, regardless of which version of the game you play. However, on the ''Luigi's Mansion'' racetrack in ''VideoGame/MarioKartDS'' & ''VideoGame/MarioKart7'', the mansion contains the PAL/Japanese version of the King Boo & Bowser painting. This makes it really hard to tell which version of the painting you get at the end of ''Luigi's Mansion'' is the real painting.

* ''VideoGame/LuigisMansion'' has a rather strange technicality here - there are two versions of the King Boo & Bowser painting you can get at the end of the game: one in the US version which has King Boo and Bowser facing to the left, and the one in the PAL & Japanese versions which has King Boo & Bowser facing each other. The credits in Luigi's Mansion show that the US version of the painting is the real one, regardless of which version of the game you play. However, on the ''Luigi's Mansion'' racetrack in ''VideoGame/MarioKartDS'' & ''VideoGame/MarioKart7'', the mansion contains the PAL/Japanese version of the King Boo & Bowser painting. This makes it really hard to tell which version of the painting you get at the end of ''Luigi's Mansion'' is the real painting.

* ''VideoGame/Luigi'sMansion'' has a rather strange technicality here - there are two versions of the King Boo & Bowser painting you can get at the end of the game: one in the US version which has King Boo and Bowser facing to the left, and the one in the PAL & Japanese versions which has King Boo & Bowser facing each other. The credits in Luigi's Mansion show that the US version of the painting is the real one, regardless of which version of the game you play. However, on the ''Luigi's Mansion'' racetrack in ''VideoGame/MarioKartDS'' & ''VideoGame/MarioKart7'', the mansion contains the PAL/Japanese version of the King Boo & Bowser painting. This makes it really hard to tell which version of the painting you get at the end of ''Luigi's Mansion'' is the real painting.

The heroes encounter a situation where the villain is an imposter of one of their own and/or a sympathetic character. The heroes must find out about the imposter and expose him/her to stop him.

Typically, the situation will involve the impostor and the real person standing side-by-side, both claiming to be the real one, and the other heroes must use their wits to identify who is who, usually by finding a quality that the faker doesn't have (in comedic examples, a positive quality). Or the real person may ask that their friend [[KillUsBoth shoot both of them]] just to guarantee they get the imposter (and it's almost inevitable if the person has a [[HealingFactor super-healing power]]), which usually results in the heroes shooting the other one, because the impostor [[DirtyCoward wouldn't be noble enough]] to suggest making the HeroicSacrifice. This is often parodied these days where the imposter suggests it, knowing they'll assume the noble act to mark them out as the original — and sometimes double-parodied when this ends up outing him as the fake since [[{{Jerkass}} the real person wouldn't be so noble]].

In videogames, often the two clones will be desperately attempting to beat the crap out of each other while the player struggles to figure out a means of telling them apart, often with one tackling the other, punching him a few times until the pair rolls over and the person on top switches, ad nauseam (which conveniently allows a very short looping animation to represent the whole fight).

A common subversion is for the protagonist to either shoot in a blind guess that turns out correct, or simply shoot both and see who gets madder. In both situations, the victim of the imposter is likely to be incensed that the hero couldn't tell him from his doppelganger.

The real person's {{nervous tic|s}} can also be useful in exposing the imposter.

* Taken to the next level by Karl on ''Radio/TheRickyGervaisShow'', whose stupidity was such that he did not like the idea of having a clone on the basis that [[WhatAnIdiot he wouldn't know which one he was]].

* ''Anime/DoraemonGreatAdventureInTheAntarcticKachiKochi'' have the gang, exploring a set of ruins, being ambushed by Yamitem, a hostile, shape-shifting robot who wants to kill all intruders, firstly by capturing Doraemon alive and then impersonating Doraemon to rendezvous with the others, intending to lure everybody to a SpikedCeiling trap. The ''real'' Doraemon regains consciousness in time to warn everyone, leading to an intense moment where the gang must [[https://www.youtube.com/watch?v=3l1EOL2mSJU identify which Doraemon is the real deal]]. [[spoiler: Ultimately, it's Nobita who managed to identify the ''real'' one by [[EyesAreMental looking at their eyes]] - Nobita's friendship with Doraemon is far more powerful than anything Yamitem's shape-shifting abilities could create]].

* Happens in ''VideoGame/YakuzaLikeADragon'', when Adachi gets wrangled into a struggle with Mirror Face, an assassin disguised as him. Since Adachi worked at the DMV, Ichiban decides to quiz them on traffic laws, with one answering accurately and the other being utterly baffled by them. [[spoiler:Ichiban proceeds to punch out the one who answers accurately, leading to Mirror Face lying on the ground wondering how someone like Adachi even kept his job in the first place]].

* An early episode of ''Script/AHDotComTheSeries'' has a ShoutOut to the ''Series/RedDwarf'' example above, when the crew pick the real Doctor What from his Mirror Universe EvilCounterpart by rapid-firing questions about Paris Hilton at him. Later [[ContinuityNod referenced]] when a ''different'' EvilCounterpart's deputy tries to use it, but the real Doctor What quickly shouts out the "right" answer and thus she picks the wrong one.

* ''Film/IceColdInAlex''. The MainCharacters begin to suspect that the South African officer who hitched a lift with them may be a German spy because he doesn't know how to brew up a SpotOfTea in the preferred method used by South African soldiers.