When you look into a mirror, you see a person who is in some ways identical to yourself, but who is also in some ways your opposite. If you are right-handed, your mirror will show a left-handed person, and vice versa.
This "same but opposite" is the cornerstone of a Mirror Universe. A character's "same but opposite" counterpart is the Mirror Self. However, a Mirror Self can sometimes also be created by misuse of Applied Phlebotinum.
Not to be confused with an Alternate Self, who is the same person without being an opposite. Might have gone through different experiences and been changed by them, but is not a polar opposite like the Mirror Self. Compare Me's a Crowd.
- Subverted in Cardcaptor Sakura by the use of The Mirror card which creates an exact copy of Sakura that she can then control. Before her capture The Mirror appeared to be a mischievous opposite version of Sakura but this is likely just the personality of the card itself and not because it's Sakura's reflection.
- Played for laughs in an episode of Slayers. An evil wizard uses a mirror that brings to life the subject it reflects. In a flash of light, the heroes are face to face with exact mirror duplicates of themselves. They run off screaming because they are cowards where the originals are brave adventurers.
- In The Smurfs story "The Hundredth Smurf", a Smurf's mirror is struck by lightning, which brings his reflection to life. The reflection speaks backwards and does everything the original Smurf does, but in reverse (lifting the right arm when the other lifts the left, for instance). After he causes chaos in the village by his opposite nature, the reflection decides to return to the mirror, but he goes through it instead, and comes out a regular Smurf.
- John Byrne retold Donna Troy's origin in Wonder Woman so that she was originally the mirror self of Princess Diana as a teenager, but given a separate personality by the sorceress who owned the mirror. Donna Troy was then captured by Queen Hippolyta's nemesis Dark Angel, who mistook her for Diana, and subjected her to live multiple lives that all ended in tragedy, ultimately leading to the one where Donna becomes Wonder Girl/Troia of the Teen Titans. This origin has recently been retconned out of her history since 2006.
- Conan the Barbarian once visited a parallel universe to meet Conar, a bastard coated with bastard with bastard filling as opposed to his jerk with a heart of gold nature. No less of a badass and favored of the fates, Conar had already won his throne by that time, and it turned out the arrival of Conan foiled an assassination attempt by some would-be usurpers. After a fight to a standstill (after winning the hearts or more of some of his mirror self's subjects, including the wife and the mistress), Conan left the mirror world, justifying the act as leaving the throne to its rightful owner.
- In Empath: The Luckiest Smurf, Vanity's Mirror Self goes by the name of Century, but in "Vanity's Double" shows that he isn't afraid of swords or swordfighting, which proves helpful when is cast alongside Vanity in the role of Robin Smurf.
- Inner Glory has the dark reflections, Evil Twins of the mane six dwelling in Tartarus:
- Twilight Sparkle, the Element of Magic (magic representing friendship in this setting): Lustrous Revolt is rude, quick to violence, callous, and demanding. ...In other words, she's unfriendly.
- Rainbow Dash, the Element of Loyalty: Spectral Slash acts like a friend to the mane six at first, but sells them out to her real allies almost immediately.
- Pinkie Pie, the Element of Laughter: Pinkamena Diane is depressed, bitter, sullen, and always serious.
- Rarity, the Element of Generosity: Temperament totally scams Twilight, and generally acts very greedy.
- Fluttershy, the Element of Kindness: Shuddercry is a sadistic Jerkass who enjoys bullying others.
- Applejack, the Element of Honesty: Jackie is a (surprisingly nice) pragmatist who has no problem lying to get what she wants.
- The Bleach fanfics Phases of the Moon and Chasing the Moon feature Jungetsu, Kurosaki Yuzu's zanpakuto spirit. She appears as a perfect copy of her wielder, except all of her wielder's features are reversed, including handedness. This is actually combined with Revealing Injury later on, when Jungetsu takes Yuzu's place in the world of her bankai to trick and distract Byakuya from finding the real Yuzu. Byakuya discovers the fake by noticing that a scar was on the wrong arm.
- Scott Pilgrim vs. The World has "Nega-Scott". Subverted. Other than his Dark Link appearance he's exactly like Scott and they get along swimmingly.
- In The Dark Crystal, the "good" urRu/Mystics and the "evil" Skeksis are split beings, formed from a race (the "urSkeks") not native to the world of the film, and who were formed when the Crystal itself was split. Each Mystic has a Skeksis counterpart, and if one dies, so does the counterpart.
- The Callahan's Crosstime Saloon story "Mirror/rorriM Off The Wall" has a Mirror Universe where everything is in reverse/backwards, including handedness and fingerprints. One of its inhabitants is a Mirror Self of someone in our universe: they're both named Robert Trebor.
- In Pact, Blake and Rose Thorburn are reflections of each other born as different genders. Only one can inhabit the real world at a time-the other is trapped in an empty mirror world created by light shining through mirrors in the real world.
- One of the earliest Star Trek novels, "Spock Must Die!" involved a transporter accident duplicating Spock. As such things go, of course the clone is evil, but Kirk and the others can't tell who is who. They eventually figure out that since the copy was created by a reflected transporter beam, it is reversed left-to-right, right down to the molecular level. He can only survive on special synthesized food, because his body is made of backwards amino acids.
- In Karl Marx's "Scorpion and Felix," the author hears a voice saying that it will prove the opposite of what he said. It turns out that this voice is 'himself.' He turns around to check who said it, and sees himself there. His first thought is that he is a 'doppelgänger.'
- In the Star Trek universe, there is a Mirror Universe where every character has a Mirror Self. Good characters generally have evil Mirror Selves, and vice versa (there are exceptions, like "Smiley" O'Brien). Ambiguous characters often have their defining traits reversed.
- The Doctor encounters mirror counterparts of the UNIT team in the Doctor Who serial "Inferno".
- In Charmed, the Mirror World has a Mirror Self of every character, just like in Star Trek. The characters also have alignment-shifted powers, creating oxymorons like the Demon of Hope.
- It's not really an oxymoron, because demons are the good guys there.
- It's not impossible for hope to become figuratively demonic.
- Thelonious Monk is reflected in mirror images on the album cover of Brilliant Corners.
- In Calvin and Hobbes, one story arc features Calvin making a Mirror Self of himself. The real Calvin doesn't want to do his homework or clean his room, but his Mirror Self is a well adjusted polite little boy who gladly does these things... and proceeds to destroy his life by being way too nice.
- In The Wacky Adventures of Pedro, Pedro's efforts in constructing a mirror portal turn his reflection into an Evil Twin named Ordep. Later, the mirror also turns Ordep's reflection into the goody-goody Erpod.
- Using the right spells in Dungeons & Dragons allows characters to enter the Plane of Mirrors, a transitive plane that uses a set of mirrors as a Portal Network - the catch was that entering it created an opposite-alignment mirror counterpart (opposite primary hand and all) that would try to kill you and take your place in the "real" world. An adventuring party that pursued a foe onto the plane ran the risk of encountering its very own band of Psycho Rangers... as well as one potential ally.
- Close to the end of Quest for Glory III. Each hero was forced to fight a twisted mirror image of him- or herself.
- The final boss of the Old Kingdom instance in World of Warcraft summon mirror versions of the heroes for them to fight.
- In Zelda II: The Adventure of Link, Link has to do battle against a mirror image of himself. He was so popular that "Dark Link" has shown up several times since then.
- In Final Fantasy IV, when Cecil becomes a Paladin he must fight a mirror image of himself to atone for his past.
- In Prince of Persia, the Prince, at one point, has to jump through a mirror, which sets his reflection free, who is pretty much the game's most memorable villain. It makes a few appearances throughout the game generally being a jerk, until he has a level dedicated entirely to dealing with it.
- Kingdom Hearts 0.2: Birth by Sleep - A Fragmentary Passage features four separate battles with Aqua's Mirror Self created by the Magic Mirror of the darkness-corrupted Dwarf Woodlands. Three are mandatory and of steadily increasing difficulty, while the fourth requires beating the game once and performing a sidequest to unlock the Boss Rush, at the end of which awaits the immensely powerful Zodiac Aqua.
- Near the end of Death Gate, your path is blocked by a mirror version of yourself. Since he's just as strong as you and matches your moves exactly, you can't force your way past him. The solution? Cast the self-immolation spell, but choose runes that make a mirrored pattern. He will cast the same spell, but whereas yours will be wrong and do nothing, his will work - and destroy him.
- The first edition of Tomb Raider has one of the zombies mirroring Lara Croft in one of the lower levels. Everytime she moved, the zombie moved. The solution was to get the zombie to fall into a hole in the floor, trapping it.
- Played with in The Non-Adventures of Wonderella. Everybody in the mirror universe has the opposite moral alignment of their normal self — except for Wonderella and Dr. Shark. As the mirror-world's Wonderella explains it:
Anti-Wonderella: The opposite of neutral is still neutral!◊
- In Dark Legacy Comics, it turns out that the characters have mirror selves on the other side. The protagonists are alliance characters in World Of Warcraft, so their mirror selves are horde. This make at least one character frustrated◊ and at least one (*2) character(s) happy.◊
- Homestuck: The Scratch mechanism in Sburb and Sgrub sessions basically creates these — your ancestor will take your place in life, down to living in your house, and usually shares a decent amount of your personality as well as your Aspect in the game, but they're not a direct copy.
- The Inexplicable Adventures of Bob! has Molly's clone Galatea. Where Molly is a cheerfully childlike genius ditz, Galatea is equally brilliant, but paranoid, neurotic, and frequently hostile.
- In The Batman, Batman, Robin, and the Flash dealt with mirror versions of themselves created by the inventions of the Mirror Master.
- It's a commonly held belief among many conspiracy theorists that mirrors are among the 10 secret mind control symbols that appear all throughout the media and that they represent "alters" or artificial personalities that were created by a performer's Illuminati mind-control programmers or "handlers". The main four alters are alleged to be "alpha" (general), "beta" (sex), "delta" (killer) and "theta" (psychic} with beta being the most common. Mirrors are considered to be important in Illuminati programming because the the mirrors create internal images. Within the Monarch slave's mind countless mirror images are made. The person seeing a different person in the mirror is said to be a powerful MK Ultra mind control symbol. According to the tinfoil hat crowd, mirrors also serve as a hypnotic trigger for the performer in question. For example, this photo of Cindy Margolis, which appeared in the July, 2008 issue of Playboy has two mirrors and she's looking in one of them. They also claim that having half of her face shadowed indicates a Split Personality and the fact that she's naked emphasizes that Cindy Margolis is looking at one of her beta ("sex kitten") alters.NSFW
- A lot of people who appear on reality television are often shocked and embarrassed when seeing their behavior in the third person, as not many people get to see themselves the same way others see them.