History Main / EyeDentityGiveaway

** Envy is a LivingShadow who can shapeshift into anyone she chooses when she's not possessing them anyway. In both instances, shapeshifting and possession, her red eyes are her dead giveaway Envy shapeshifts into Rarity at one point to emotionally manipulate and drive a wedge between Nova Shine and Twilight Sparkle, yet, even though she wears Rarity's shape, Nova notices her red eyes but doesn't react given the situation she confronts him in. Come [[FanFic/TheArchmagesLastBow the sequel]], Envy taunts him over the fact that he never realized who she ''really'' was, given the pony Nova thought she was didn't have red eyes at all up until her supposed FaceHeelTurn.

* ''Film/XMen1'': At the very end, Senator Robert Kelly returns to Congress on television, but his eyes briefly flash gold on-camera, which the X-Men notice and deduce that the Robert Kelly on-screen is Mystique in disguise.

Heavy overlap with EyesAreMental, although that trope is specific to shapeshifters who can't disguise their eye color. A SubTrope of EyeColourChange, and may also be one for RedRightHand if the character is an antagonist, and even further if they have red eyes when they take over, then it overlaps with RedEyesTakeWarning. Overlaps slightly with MindControlEyes. May also overlap with GoodEyesEvilEyes if two beings in one body that are on opposite ends of the moral spectrum have distinct designs. Similar to MorphicResonance, which is when characters transform into things that resemble them as people, whereas here, the eyes are the only link to their usual identity or appearance. See also EyeMotifs when eyes are symbolic of certain themes, but not dead giveaways for characters themselves. Not to be confused with EyesNeverLie, as that is when a character's eye movements give away their intentions.

* ''Literature/WarriorCats'': In the seventh arc, ''The Broken Code'', the spirit of [[spoiler:Ashfur]] uses the opportunity of Bramblestar [[CatsHaveNineLives losing a life]] to take over his empty body between lives and pretend to be him. In ''Veil of Shadows'', when he loses his temper, Bristlefrost notices that his eyes look blue for a second - the impostor's natural eye color - rather than Bramblestar's amber. This helped confirm the identity of the impostor to readers, and fans tend to include a bit of blue in the eyes when illustrating scenes from the arc.

* In ''[[Literature/HeraldsOfValdemar The Black Gryphon]]'', Urtho sees that his great enemy Ma'ar has reshaped his entire body to make it strong and beautiful, but his eyes are the same, still green and shrewd. In his later incarnations the spirit who was Ma'ar continues to remake the [[FamilialBodySnatcher bodies he snatches]] but learns how to change the eyes too.

This is more than just "this character has visually-distinct eyes from everyone else", although [[{{Foreshadowing}} that may be something that is used to invoke this trope down the line.]] What matters is that a character isn't who they say they are. An [[ImposterForgotOneDetail imposter will always leave a hint or two]], but it's only a case of this trope when it's the color or design of the eyes themselves that are one of, if not the ''only'' hint that a character is someone else.

This is more than just "this character has visually-distinct eyes from everyone else", although [[{{Foreshadowing}} that may be something that is used to invoke this trope down the line.]] What matters is that a character isn't who they say they are. An imposter will always leave a hint or two, but it's only a case of this trope when it's the color or design of the eyes themselves that are one of, if not the ''only'' hint that a character is someone else.

However, sometimes this is taken a step further, and instead of giving away information ''about'' the character, the eyes instead give away ''the character themselves'' to the audience. It could be a character in disguise, whose eyes remain the same. It could be two (or more) characters sharing headspace, and the eyes denote who's in control. What's important is that the eyes themselves are the dead giveaway as to who someone ''really'' is at a glance.

* ''Anime/MobileSuitGundamTheOrigin'': Char Aznable wears CoolShades, and later a CoolMask, almost constantly claiming he has a pigmentation issue with his eyes. This is to hide the fact he has blue eyes which doesn't match up with documentation saying that the real Char has brown eyes. The real man behind the mask and glasses is Casval.

* ''WesternAnimation/GravityFalls'': When Bill Cipher possesses a human, their eyes change to yellow sclera with black slits for pupils. In "[[Recap/GravityFallsS2E15TheLastMabelcorn The Last Mabelcorn]]", Ford begs Dipper to look at his pupils as proof that he's not possessed by Bill, while in "[[Recap/GravityFallsS2E17DipperAndMabelVsTheFuture Dipper and Mabel vs. The Future]]", Bill is able to trick Mabel into making the deal that releases Weirdmageddon because he was hiding in Blendin Blandin, [[InhumanEyeConcealer who wears opaque glasses]]. When Blendin takes them off to reveal his eyes, Mabel has a horrified moment of WhatHaveIDone before getting put to sleep.

* ''WesternAnimation/GravityFalls'': When Bill Cipher possesses a human, their eyes change to yellow sclera with black slits for pupils. In "[[Recap/GravityFallsS2E15TheLastMabelcorn The Last Mabelcorn]]", Ford begs Dipper to look at his pupils as proof that he's not possessed by Bill, while in "[[Recap/GravityFallsS2E17DipperAndMabelVsTheFuture Dipper and Mabel vs. The Future]]", Bill is able to trick Mabel into making the deal that releases Weirdmageddon because he was hiding in Blendin Blandin, who wears opaque glasses. When Blendin takes them off to reveal his eyes, Mabel has a horrified moment of WhatHaveIDone before getting put to sleep.

* Myth/NorseMythology: Odin Borsson can turn into various animals (his favorites are ravens and wolves), but, like him, they are easily identifiable by his missing eye.

* In ''Literature/DrFranklinsIsland'', two castaway girls are [[ForcedTransformation forced]] into a SlowTransformation. Miranda, changing faster, is a twisted wreck when the doctors take her away from Semi, who thinks that by that point the only part of her still recognizably Miranda is her eyes - though those have changed as well by the time Semi sees her again as a bird monster. Semi becomes a NearlyNormalAnimal mostly resembling a MellowManta, but she retains brown human-looking eyes, although her [[BlindWithoutEm myopia]] is corrected.

* ''WesternAnimation/Ben10AlienForce'': All of Ben's aliens share his green eye colour (when their eyes are visible, at least), including appearances of ten-year-old Ben's aliens in ''[[WesternAnimation/Ben10UltimateAlien Ultimate Alien]]'' and ''[[WesternAnimation/Ben10Omniverse Omniverse]]'' that originally did not. In [[Recap/Ben10AlienForceS3E20TheFinalBattlePart2 the finale]], Gwen identifies Swampfire as Ben via his green eyes rather than his EvilTwin Albedo's red.

* ''WesternAnimation/SheRaAndThePrincessesOfPower'': Double Trouble can disguise themself perfectly, but they sometimes shift back to their regular lizard eyes when they blink, giving them away.

** There are a number of physical differences between Yugi Muto and the entity that resides in the Millennium Puzzle, although he and Yugi look mostly the same. The two most apparent, however, are that the entity's AnimeHair has some additional golden spikes and that his eyes, in contrast to naive Yugi's [[https://64.media.tumblr.com/1cff0827bcfabdbcda0a0118df1c0040/94a8cdbf51da206a-aa/s400x600/52e65b992b7e97b99b6c1c2d5674bf3d4769d005.jpg round and wide eyes]], are [[https://static.wikia.nocookie.net/yugioh/images/8/81/Dark_Yugi_-_Duel_233.png/revision/latest?cb=20171125124202 narrow and angular]], befitting his colder and more malicious personality.