Don't you hate it when you've drawn a bead on that pesky Ninjamek, and you're just about to blow him into scrap, when he starts appearing all around you, and you can't be sure which one is real and he's everywhere and you can't possibly get them all in time and you keep shooting and shooting but they keep coming and aaaAAARRGH!!!!
Common "attack" used in anime, usually by the opponent of the main character. They will create (or clone) multiple copies of themself, frequently encircling the target.
One of these copies is the real one, while the rest are just harmless illusions to distract their target; said target must find a way to "sense" which one is the correct one and attack it, before the entire group closes in to strike.
In video games, finding the "real" one usually boils down to a game of "one of these isn't like the others", by noticing subtle details like whether they use the same attacks, have the same HP or defense power, or cast a shadow on the ground.
A common diversionary tactic with Ninja.
If the copies are tangible enough to be a threat on their own, independent of whichever is the "real" one, it's a Doppelgänger Attack. For the use of tangible doppelgangers outside of combat, see Me's a Crowd.
The practice of seeing through the illusions to attack the "real" one can be thought of as a type of Shell Game. Spotting the Thread, Spot the Imposter and especially Imposter Forgot One Detail are related tropes, playing with the idea of spotting small differences in a way often very similar to this trope.
This is what the "Double Team" move does in Pokémon.
Played straight as an arrow during Suicune's testing of Janine in Pokémon Special. Janine and her Crobat fly into the air, split into a ring of Double Team clones, and dare Suicune to find the right one. After being beaten, the ninja Leader realizes that Suicune identified the real Crobat by the darker shadow underneath it.
Fun fact: Double Team's Japanese name is "Kage Bunshin", or "Shadow Clone/Divide".
Cologne from Ranma ½ executes this maneuver against Ranma in one of their first battles, called the "Splitting Cat Hairs". Since she was so hungry Ranma made the real one jump out when he threw a piece of chicken in the air.
This is one of the basic ninja skills in Naruto. All ninjas learn how to make illusionary copies of themselves with the "Bunshin no Jutsu (Clone Jutsu)".
Naruto cannot perform the normal Bunshin no Jutsu, which should only make up to three illusory clones. He instead does Kage-Bunshin no Jutsu (Shadow Clone Jutsu) which are far more solid (as in they can actually hit things), are only limited in number by the amount of chakra available, and have the added advantage of whatever they learn before being dispelled, Naruto will learn once they are.
A semi-common technique in Dragon Ball. It's called the "After-Image Technique" and lets the user leave an image of themselves behind while they attack from a different angle.
Also subverted by Agent Purple/Ninja Murasaki; he has the ability to appear in five different places at once... because he's one of a set of identical quintuplets.
Hiei from YuYu Hakusho uses something similar to the Dragon Ball example above, using extreme speed to leave an afterimage. It's only one at a time though, and only used as a defensive technique to escape injury.
This is a favorite trick of Lyrical Nanoha's illusionists. The more skilled practitioners, like Teana and Quattro, are capable of creating duplicates that can fool even radars and sensors.
Shinomori Aoshi uses something like this in Rurouni Kenshin as a psych-out lead-in to his Kaiten Kenbu attack: several images of Aoshi begin circling his opponent until the real one attacks. Used mainly for intimidation (since the apparent copies don't do anything threatening).
Kenshin has, arguably, something similar with the Kuzu Ryuu Sen attack. The wielder doesn't actually appear in more than one place, but their sword does, since the technique hits nine different spots at almost the same time, making it impossible to block or dodge. Naturally it's been dodged once (by Soujirou), blocked once (by Enishi), and stopped in mid-execution (Enishi again).
Killua Zaoldyeck from Hunter × Hunter has this ability as part of his assassin's training since birth.
In a later arc, a pair of Hunters (Morau and Knuckle) work together to produce a variation of this. Morau controls smoke, which he forms into multiple smoke clones of Knuckle to hide amongst.
Shijima pulls this off in Ninja Scroll. Jubei cuts through all of them at once, severing Shijima's lower leg.
Unusually, this ability is given to one of its heroes; Ichigo, with his new Bankai, pulls this off during his fight with Byakuya.
Also used in almost the exact same way with Yourichi and Byakuya himself. The dopplegangers are actually so realistic that they show damage before fading away. Yourichi get's slashed by Byakuya, Byakuya by Zomari LeRoux. Both times, the dopplegangers fade away, after which the real one reveals him/herself. Zomari himself is also quite skilled at creating afterimages.
Used by the assassin Kuzuryū, who attacks Uryu in anime episode 176. He creates a mist that generates illusionary images of himself.
Soifon can do this as well.
Used by the villain Kouga during anime episode 252. He fools Byakuya Kuchiki's senses so that he sees multiple false image of Kouga, preventing from attacking the real one.
Used by a rather ghostly opponent in Medabots, until someone started shining a light on all the projected images.
Used by one of the Snow Dancers in the Sailor Moon S movie. Sailor Moon attempts to single out the real one and, unsurprisingly, chooses wrong.
In Part 3 of JoJo's Bizarre Adventure, Polnareff's Stand, Silver Chariot, displays this ability after it sheds its armor during his fight with Avdol (and he only uses it during this fight). He explains that he doesn't actually have multiple Stands, Silver Chariot simply moves with such speed that the human eye only thinks it sees multiple copies of it.
Ryoko's done this in the Tenchi Muyo! manga a few times. I only remember one anime appearance, and it was more for a con artist deal than combat, but the manga had her doing it in a more hostile vein. She's also capable of creating physical clones, at least in the OVA continuity.
Played straight by a ninja in Airmaster and then parodied by his dim-witted opponent who solves the problem in unorthodox fashion by attacking each image until they hit the right one.
In Gundam F91, the titular mecha can shed the outermost layer of its ablative armor (which is apparently hundreds of layers thick), leaving behind an afterimage that appears real to most sensors (since Minovsky Physics are in effect, sensors are a lot more limited in than in real life despite the otherwise far more advanced technology). This does, however, straddle the line between Doppleganger Spin and Speed Echoes. This becomes highly important in the final climactic fight.
In Fist of the North Star, someone tries this on Kenshiro. Kenshiro spins around while punching and hits the guy hundreds of times.
Nami from One Piece is capable of manipulating weather conditions with her weapon. This includes creating mirages to confuse enemies. They don't exactly look identical, but don't go assuming that the one that looks like the real deal is her.
In Flame of Recca, the Genjutsu Wakemi is a technique created by Genjuro and passed on to Kurei that does exactly this for the user. Problem? You can't copy items held in your hands, only your body and clothing.
In the Naruto parody reaction episode of Yakitate!! Japan, Suwabara Kai also uses several Spring Onions to do this trick.
Done with a fairly ridiculous justification in Soul Eater, where Black Star moving fast enough somehow left his shadow behind giving his afterimage mass. He can also increase the effect even more by having Tsubaki transform into him.
Yaiba uses such a trick in the first volume against Sayaka's grandmother. After a brief beat, she knock him down with a single well-aimed hit on the head. She comments though that it wasn't very easy.
In the Blade anime, Blade gets this in the form of "Deadly Sword Technique #1: Residual Moon". The illusory copy even looks like it takes damage. This confuses the enemy long enough for the real Blade to attack from behind.
In Reika's first fight as Cure Beauty in Smile Pretty Cure!, she's able to find the real Monster of the Week by attacking the one that's a "mirror image" of what the others look like (the other four girls just aimed randomly, not realizing that bit.)
Parodied in an episode of Samurai Pizza Cats. Guru Lou develops a machine designed to do this, but when Guido tries to use it, the clones turn out to be a series of folding panels that clumsily extend from the sides of the machine, not to mention that the pictures produced are of Speedy, not Guido.
The Getter-2 line of Getter Robo has this with their "Getter Vision" ability, moving so fast that it creates after-images of itself.
Mobile Fighter G Gundam has God Gundam's "God Shadow" technique, in which Domon creates copies of the God Gundam at will... just to catch Chibodee's ultimate attack.
R Obin Mask does this during his fight against Junkman in Kinnikuman; the Devil Choujin has a second face growing out of the back of his head, so Robin tosses his armor off to increase his speed and run around him, making the villain dizzy. Then Robin gives him the Tower Bridge.
In World Conquest Zvezda Plot, White Falcon uses this against General Pepel during their fight. All of the images circling around General Pepel turn out to be fakes, the real White Robin performing an aerial attack from above while he's distracted.
Iron Man used this trick a lot in the old days, courtesy of his suit's built-in image inducer. Nowadays Tony can control machines with his brain, so he likes to use real Iron Man suits as the "dummies".
Then there were the few times when he was using remote-controlled suits or simply having his friends put on extra suits to give him some back-up.
British 1980's Starblazer comic. The Clone Burst device created multiple holographic copies of the user as a decoy.
In the Sonic the Hedgehog comic, Sonic tended to use this from time to time, using his super speed to confuse his opponents.
Both Jair Ohmsford and Walker Boh liked this trick in Terry Brooks' Shannara series. Jair used it in particular during his battle with his sister in Wishsong, and Walker used it as a distraction in the climactic confrontation with the Stone King in Druid.
Walker uses it again in Talismans to face off against the Four Horsemen of the Apocalypse. The trick is that the Walker they're fighting isn't real at all, just an image he's projecting to make them kill each other. Death sees through the illusion, however, and almost kills Walker.
In The Dresden Files Molly does this in Ghost Story. This makes Harry's incorporeal jaw drop, as she creates 6 perfect copies of herself and veils herself at the same time.
Robin McKinley's Spindle's End, a reworked version of Sleeping Beauty, has the heroine and a group rescue her friend, and mirror images that can attack are used (, including a overly-friendly dog that licks the enemy into submission).
Live Action TV
In Kung Fu the Legend Continues, Caine uses this (Called the 4 winds) to confuse his enemy "The Dragon's Daughter"
In Smallville, Collateral, in order to confuse Clark and keep him in the world of the Lotus-Eater Machine, a bad guy created at least six copies of his best friend, Chloe Sullivan.
Star Trek: The Next Generation's Captain Jean-Luc Picard is credited with the creation of the eponymous "Picard Maneuver," in which a starship makes a short-distance warp jump, effectively outrunning light and thus creating an "afterimage" of the ship in its former location.
Which is totally preposterous. Starships must have some sensor system to prevent this already, lest the ship be perpetually surrounded by sensor phantoms of ships that had long ago left, but hey, Rule of Cool, right?
Later justified in the Star Trek: The Lost Era book "The Buried Age": It was an unexpected maneuver because it would divert power from the weapons and shields; the enemy was relying primarily on short-range, light-speed-limited Tactical sensors in the heat of the battle; but above all, they needed to do something drastic, and they wouldn't get a second shot.
It makes sense the first time it's used, as it's explicitly stated that it was used against a less advanced Ferengi ship which only had light speed sensors. When a brainwashed Picard uses it against the Enterprise, however... uh... well...
Star Trek: Voyager later managed to pull off their own version by installing hologram projectors on the outside of the ship.
Although in this instance, they didn't create exact copies (since their attackers know they're the only ship in the quadrant), and instead create several generic ships as if part of an allied fleet.
This is exactly what the spell Mirror Image does. Using Mirror Image is a standard defense mechanism for mages in all Dungeons & Dragons-based games.
It got even better with higher-level versions from Dragon Magazine. "Image Trap" is much the same with a melee-range Color Spray from each shattered decoy. "Crew of Phantoms" creates twice more duplicates for up to 30 people at once, i.e. up to 150 phantoms in average if you aren't low on originals.
The cloaker monster could manipulate shadows to create images of itself to fool opponents, thus acting like a Mirror Image spell.
A natural version occurs in the "Revenge of the Mountain Clan" segment of the Basic D&D module CM1 Test of the Warlords. The crystal stalagtites lining a room create 11 false images of a gargantuan troll in the room, which means that each time a PC hits a troll there's only a 1 in 12 chance that it's the real troll.
Champions supplement Gadgets!. One of the title items was the Multiple Image Projector, which created four images of the wearer in a group around him.
Shadowrun. The Double Image spell in Magic in the Shadows creates a single illusory double.
Victoriana RPG supplement Faulkner's Millinery and Miscellanea. The magical Mirrorcane can create three illusionary images of its wielder to distract opponents.
Star Frontiers, Dragon magazine #88 article "The Battle at Ebony Eyes". A natural version of this occurs in the Ebony Eyes star system. A pair of black holes orbit each other 160,000 kilometers apart, resulting in severe disruptions in the local space-time continuum. This causes the appearance of one, two or three illusionary duplicates of any objects in the area, such as starships.
Mage: The Awakening has this as a high-end Space Arcanum spell. "Co-Location" creates a number of doppleganger images and the caster can reflexively teleport between them, acting as a limited form of Teleport Spam.
Some Goblins can create 2-5 illusionary duplicates of themselves that mimic their every action.
Leprechauns can do the same thing, but have complete control over the illusions' actions.
Warhammer 40,000's Dark Eldar have access to an ancient piece of technomagical equipment called a Clone Field, which produces this very effect. The Master Haemonculus Urien Rakarth is known to have one.
Courtesans supplement The Weird and the Wonderful. The "Courtesans 20,000" section has Space Elf Diversion Projector armor, which creates realistic holograms of the wearer to distract attackers.
A form of this trope also appeared in the original game in the series, in the graveyard. Touching the tombstones released ghosts known as Ghini, all of which were unkillable except for the "lead" Ghini on a particular screen; killing the lead Ghini defeated all of them at once. It was fairly easy to identify the lead Ghini, as it was more opaque than the others, but it was vexing in that while you couldn't hurt the other Ghini, they could most definitely hurt you.
The original Ghini also moves differently than the others (moving in the cardinal directions as opposed to diagonals only, if memory serves).
Phantom Ganon does this too in his first two appearances, in Ocarina of Time and Wind Waker. In Ocarina of Time, he disappears into a painting of a spooky road in his boss room, and several of him ride back (he rides a horse here). The real ones creates a portal and comes out and the rest turn back at the last second. In Wind Waker, he gets simple and only surrounds you, and the real one is always the one behind you.
So does Split Mushroom against X or Zero in Mega Man X4. Not only that, but he also has an attack that spawns a large number of copies and sends them out as projectiles.
In Mega Man Star Force, Gemini Spark comes in two forms, White and Black, that you face at the same time. Both of them can hurt you, but you can only hurt the one with the HP under him.
Until the sequel, where both White Gemini and Black Gemini each get their own set of HP.
This is one of the "ninja powers" used by Ken in the "Canned Heat" stage of Elite Beat Agents; if the player is failing when that cutscene comes up, Ken and all of his doppelgangers fall over dizzy afterwards.
In Cannon Spike, the boss Psychiccer Sting will create three illusions of himself, only one of which can be hurt.
A rare PS1 game called Krazy Ivan had a boss called Reflex, which can split into 3 copies, of which the fake ones are easily destroyed.
A few moves in SaGa Frontier- "Mirror Shade" allows you to create up to 5 illusory dummies, while the "Magician" Arcane spell combines this with Doppelganger attack- While you can only make one dummy per turn, if attacked it's an instant death for the attacker.
Recurring Psycho for Hire Yuber from the Suikoden Series has this ability, with the twist that they're ALL real. As shown in the Suikoden III manga this means the attack can be rather deadly indeed.
During the Inevitable Tournament in the second chapter of Dragon Quest IV, Princess Alena faces off against a monster named Linguar in the final round, who uses this against her. Only one of the clones attacks at a time, but this is usually after she's selected her target, so she only has a 25% chance of damaging the Linguar. Thankfully, the Linguar's HP are lower than those of the Rogue Knight Sampson from the previous round, so two or three direct hits will KO the monster in short order.
Starcraft and Warcraft III both play this one. In Starcraft, the High Templars can create several illusions out of any unit, while in Warcraft III, the Blade Masters can create several illusions of themselves.
It also found its way in World of Warcraft eventually, as a mage spell. It's different in that the Mirror Images attack on their own but are fairly easy to tell apart from the original since they have much less health (The blademaster illusions had the same amount as the original but took more damage). Some bosses also use variations of this.
In both the original and update versions of Scholomance, the boss Jandice Barov periodically vanishes only to reappear alongside dozens of illusions of herself. The original was a Doppelgänger Attack as the fakes could attack the players, while the updated images launch fake attacks to distract players from finding the real one.
The first boss in the Temple of Ahn'Qiraj periodically disappears before reappearing along two mirror images of himself.
One of the last bosses in Digital Devil Saga, Asura Ravana, uses a variant of this trope. He turns himself completely and utterly invisible, and you are then presented with a total of 6 identical, empty-air targets. Also, area-effect attacks doesn't work. Fortunately, you have a Waif Prophet on your side, or this battle would have been completely impossible...
Shin Megami Tensei III: Nocturne does this twice: the first time is a boss battle where the enemy, Ongyo-ki, splits himself into four. Again, area attacks don't work, and if you hit the wrong one, you lose your turn. Only the real one has a shadow, but said shadow only shows up during a full moon. Later, another boss, Mot, disguises itself amongst six identical statues. Before you can fight him, you have to first locate the real one, and fortunately for you the reflective surface of the floor shows his true form.
Cackletta does this in Mario & Luigi: Superstar Saga. The trick is that the two duplicates can only attack one brother at a time, while the real one can attack both.
This is also one of the minigames in one of the Mario Party games where the player is surrounded by a circle of Boos and have to pick the right one based on the shadows they are casting.
The player's ability to do this is one of the defining features of the Gradius series; the option for triggering it is occasionally marked "Multiple", but is usually simply marked "Option". The term "option" is thus occasionally seen to mean one of the spun doppelgangers.
The NES version of Ninja Gaiden 2 also provides the player with a powerup with this effect, with up to two copies of the ninja trailing the player's movements and mimicking their attacks.
Phantasy Star Online had Sinow Beats which projected holograms and circled you. The trick to finding the fakes? The one with the red shoulder lights are real: all the holograms have yellow lights.
They return in Phantasy Star Online 2, though the tell for them is more subtle, instead having the fakes periodically crackle with electricity. They're also all equally capable of hurting you, which makes getting rid of the real deal quickly rather important.
The final boss of Metroid Prime 3: Corruption does this often. Figuring out which of the Dark Samus clones are fake is easy with the X-Ray Visor, but if you don't kill them quick enough, the original can re-absorb them and regain health.
The PS2 Shinobi enables you to "stealth dash" to move quickly, leaving behind a stationary image of yourself which can confuse some enemies into attacking it. Dashing many times can leave many images.
Freedom Force villain Deja Vu can clone himself at will. The key to defeating him is realizing that his clones all have shorter health bars and focusing on the original.
The original Kingdom Hearts has Anti-Sora, who periodically splits himself into three. The trick is that the real deal has a large HP bar, while the clones only have 1 HP. (There's an ability available in the early game that lets you see the enemy's HP.) Alternatively, you can identify which one is the real deal by how they fight, as the clones only have one attack.
This trick, executed through use of holograms is one of the two active abilities of the Tau Ethereals in Dawn of War, except they can use it to clone anyone on their side. Clones do absolutely no damage but draw fire, serving as useful decoys.
Tau characters in the Warhammer 40,000-derived tabletop game Inquisitor may also use holograms to do this.
A boss in Bad Dudes makes copies of himself to do battle with you; the difference is, the real one stays away.
In Paper Mario, the varieties of Magikoopa sometimes do this. Also, The Crystal King does it late in the battle.
Similarly, the Magikoopas in Paper Mario: The Thousand-Year Door do it, and Wizzerds are also capable. In all these cases, you either have to use an item, attack, or special move that hits them all guaranteed, or just guess. The latter of the two gets separate attacks for each clone, which predictably makes them very dangerous.
A wizard does this against you in Drakengard when you investigate some ruins the Cult of the Watchers left behind in the forest of the seal.
In Icewind Dale, the last dragon has an enhancedmirror image spell, where all the images move independently.
That's a Simulacrum spell. High level Wizards (in Baldur's Gate 2) can learn it as well, where it's significantly less useful.
One wonders how useful maximizing then doubling the length of the Mirror Image spell would be for the cost of making it seven levels higher in terms of spell level.
Very, when you realize that each copy can utilize the entire spell list as if the character were two levels lower. Project image is similar but doesn't act as if lower level.
Terranigma has one of the creepiest applications of this trope where, before you fight Bloody Mary you have to play two 'games' with her evil dolls. While the second game is clearly 'Red Light, Green Light', the first game is based on a Japanese rhyming children's game where 4 dolls do a doppleganger spin and you have to guess the right one. This was particularly hard because the translated poem the dolls chant doesn't convey the main point of the Japanese original- you have to attack the one that stops behind you.
This is how the 'Double Image' ability is portrayed in the various Super Robot Wars games.
Baal from the Diablo II expansion pack Lord of Destruction does this when you face him. His clone dies much faster than he does.
The only visual difference between the real him and the clone is the clone's type listing is slightly offset instead of centered, which allows players to know to target him first.
Or they can attack the copy, who is worth just as much XP as the real Baal.
The Wizard of Diablo III has a spell that summons 2 (sometimes 5) duplicates to run around the enemies casting spells (for 0 damage) from her current build. When she starts the spell, she even moves into a random position.
There is also a monster trait that enables a similar attack, often flooding the field with clones.
The Mad Monk in Conquests Of Camelot summons several illusionary doppelgangers when attacking to try and confuse the player.
One of the archer class's special attacks in Disgaea is something like this, aptly named "Doppelganger."
The Succubus in Castlevania: Symphony of the Night does this as part of her attack chain, filling up the top of the screen with duplicates. They all do the same choreographed moves, and there's no real way to play "One of these things..." other than to attack each one in turn until the real one doesn't vanish after one hit (or you 'cheat' and use an item/spell that hits everything on the screen at once).
In Final Fantasy V it is shortly used out of a real battle just as a test of the main characters strength by Wolfking Kelgar.
Used in the later Ace Combat games by AWACS jammer aircraft — enemy aircraft will be detected on radar, with 2 or 3 "shadow returns" that can be locked on to, resulting in clean misses. However, this doesn't apply to the jammer itself, making it a clear target...
Flandre Scarlet, an Extra boss in Touhou 6: Embodiment of Scarlet Devil, is able to pull off this at you as of her "Taboo: Four of a Kind" spellcard, which summons three clones. It's purely for the sake of More Dakka, though, as it's extremely easy to identify the real deal from the others (The one with a spell circle around her).
The mutated General Shun, the second-to-last boss of Legend of Kay, splits into four copies when he's not attacking. The one with a slightly darker red light coming from his amulet is the real one. Not that it really matters; the false ones disappear with one hit, there's enough time to hit all four of them, and it's really tricky to get more than one hit on the real one before he starts attacking again.
In Klonoa 2, the boss Leptio breaks into four copies. The real one spins at a different speed.
In Iji, Komato Assassin Asha does this in your second fight with him. Fortunately, they're all faded out and hence obviously not him. Unfortunately, Asha's MO is a very fast Teleport Spam and hence it can confuse you for the moment necessary to screw you over.
In Captain America and the Avengers, the Mandarin can create duplicates of himself, though they are easily identifiable (darker than Mandarin himself) and block your path to Mandarin rather than try to confuse you.
In Demons Souls, the Fool's Idol creates duplicates of herself as her HP are depleted. The fakes only shoot weak Soul Arrows at you, but the real one uses the upgraded Soul Ray.
In Emperor: Battle for Dune, the Ixian projector tank could produce copies that would disappear as soon as they were shot or came into contact with an enemy, but allowed for feints and other distractions. Unfortunately, their ability to do damage was not removed, making the unit somewhat of a Game Breaker, as you swamped the enemy with massive hordes of free units, their rate of production limited only by how quickly the previous projection could get out of the way.
In Dragon Age: Origins, the Lust demon possessing Connor does this in the Fade, not as an attack, but to stall for time while healing. Apparently it takes all her concentration to maintain the duplicates, as she does nothing else when they appear.
Each ninja character in Samurai Warriors series display this ability at one point when fought.
And while we're on the subject of ninjas, ninjas Hanzo and Galford from Samurai Shodown have this ability. Earthquake has this as well.
In Pokémon it's implied that Double Team does this just like in the anime; its effect is to raise evasion and all of its animations involve briefly and rapidly splitting in two, but duplicates aren't actually seen to be created and remain once the animation's finished.
When you go to capture Vanessa DeVore in the Praetor Tilman Loyalist arc in the City of Heroes "Going Rogue" supplement, this is how you face her.
In one of the instances in DC Universe Online, you face an entire room full of Doctor Psycho mind-clones.
In God Hand, the Sensei uses a multiform technique to attack Gene. The upside: the multiforms can't take more than a few hits each, and oftentimes one God Roulette super-move or one release of the God Hand's Tension can clear out all the multiforms. The downside: if you don't have either one of those ready to go when he does it, you're probably dead, because the clones all attack as aggressively and with the same moves as Sensei himself, they're solid enough to stab you, and they'll never go away until you do kill them off.
In The Legend of Dragoon, an early miniboss splits into three duplicates a couple of times during his fight. In a light subversion/twist compared to the "hit the fake and they vanish" routine, the copies take either absolutely no damage and/or have vast amounts of health, and hit just as hard as the real thing. Hitting the real one makes the duplicates disappear.
In Monster In My Pocket for NES, Medusa appears with four other duplicates. Hitting the fakes will do nothing; you have to attack the real one who soon fires and then flies straight towards you.
In Magicka, when confronting the Death, he sometimes multiplies itself and circles you; then gangers appear to come at you, but they do nothing, except for the real one, who kills you in one hit unless you counter him with a life spell.
The final boss in Assassin's Creed I uses an Apple of Eden to generate phantom copies of himself. The difference is that the copies can hurt you. Inverted at the end of Assassin's Creed II, where you are the one generating copies to confuse the final boss using a different Apple.
In Crusader of Centy, Shuffler splits into eight pieces, which all spread out four times before you can attack the real one.
The penultimate boss of Ys, Yogleks & Omulgun, consists of a pair of red and blue demon heads surrounded by orbiting objects. Only the red head can be damaged, and the two switch places after Adol scores a hit.
Automated Simulations' Star Warrior. Your character's armor could have the Decoys option. When activated (up to 3 times per game) it would release an insubstantial image of your suit which would draw enemy fire for a couple of turns.
In Chapter 2 of Dragon Quest IV, one of Alena's opponents in the tournament is a monster who spawns three copies of himself and shuffles position with the copies. Hitting a copy disperses it, but the monster then spawns a new one and reshuffles their positions again. The only way to hit the real monster and not one of its copies? Guessing. Fortunately, when you do target the real one, Alena is a lot stronger than her opponent so it doesn't take many hits to win.
Dark Meta Knight in ''Kirby Triple Deluxe generates two clones of himself in the second phase of the fight. You're given a chance to see which is the real deal before they rapidly shuffle places, then attack you. Hitting a fake destroys it but produces a projectile counterattack, and it'll be regenerated before the next attack is carried out.
La-Mulana has the enemy Hundun, whose habit of projecting copies of itself around the screen is only made more annoying by its Teleport Spamming.
Nanase uses a variation on this early on while fighting a giant blob of goo. In a subversion, none of the ones fighting the goo are the real Nanase; the real Nanase is rescuing Ellen while the goo is distracted by the duplicates. Earlier, her boyfriend Elliot complains that he hates "these trendy 'which one is real?' illusion attacks".
Magus, while "powerless", later used this to run away from more or less godlike beings.
Luna uses this trick against the Infernomancer in Dominic Deegan. When she then challenged him to find the real one, he laughed at her and attacked Dominic ("The real target is the one that will hurt you most!"), forcing her to drop the spell and rush to save him.
This is a standard tactic of Global Guardians member Los Hermanos, a duplicator who can split into nearly a thousand copies of himself.
Nomad of RuneScape summons three copies of himself in his stable combat sequence. Hit the incorrect one, it disappears. Hit the correct one, all copies disappear. All four can attack, with the real one attacking at a slightly different time.
In the original series, Hound (whose power is projecting holograms) did this once as a distraction. It worked pretty well, too.
The cartoon-only villain Luminus from Superman: The Animated Series liked to do this, but never had the good sense to get away while the getting was good. Eventually he came up with "hard light" versions of these that actually were a threat.
In Justice League episode "Only a Dream, Luminus tries the 'confuse opponent with hard light copies' technique. Just one little problem: holograms don't have skeletons.
Winx Club: Darcy of the Trix can do this with her illusion powers. During a fight in an episode of season three, she tried this trick on Nabu, only for him to dispose of the illusions with a Doppelgänger Attack.