Lost in a Crowd

For whatever reason, you find yourself being chased. You might have just pulled off the greatest heist in the history of crime. Or maybe you're an innocent man on the run, trying to prove you are innocent while dodging the cops trying to arrest you. You're dressed in a certain way, and some people who want to catch or kill you know you're dressed in a certain way. You can't change your clothing for some reason. So what do you do?

You dive into a crowd of people who are dressed exactly like you are. Hilarity Ensues. The people who are trying to get you don't know which is the real you, and start grabbing one fake after another. They tear their hair out in frustration while you casually wander away from the chase.

Sometimes, if you have a plan, you can arrange for the crowd of look-alikes to be there ahead of time. Sometimes, though, you just get lucky.

Contrast with I Am Spartacus, wherein different people try to protect you by claiming they are you, but they don't necessarily look like you, and Needle in a Stack of Needles, which is this trope applied to objects.

Not to be confused with Alone in a Crowd. See also Mobstacle Course, when you're not trying to hide in a crowd so much as merely get through one in a hurry.

Anime

 * In Code Geass R2, Zero makes a deal with Britannia to let him be exiled to an island off of China instead of killed... and then dresses up all his followers as him who, because they are all "Zero", all get exiled to that same island, which they were planning to build a base on.
 * In one episode of Lupin III, Lupin successfully convinces an entire crowd of attendees, children included, to dress as himself and his accomplices. While the police are being overwhelmed trying to arrest everyone to sort it out later, the real Lupin and company make off with an entire exhibit of things belonging to the original Arsene Lupin, as well as a model of him. This is done not only under the noses of the (heavily overwhelmed) police, but of his archnemesis Inspector Zenigata, plus a special guest antagonist, the descendant of Inspector Ganimard, who was the only man to ever arrest the original Arsene Lupin.

Film

 * Thomas Crown does this in the remake of The Thomas Crown Affair. He clearly shows himself to the security cameras wearing a trench coat and bowler hat, and carrying a valise. Then he walks off - and about two hundred confederates break out trench coats, bowler hats, and valises and start walking around the museum, switching valises many times. At some point, Crown ditches his own trench coat and bowler hat, slipping out a side entrance while everyone is looking for trench coats and bowler hats.
 * One of the uses of Queen Amidala's Impractically Fancy Outfit in Star Wars Episode I is that if all her handmaidens are dressed the same, it's hard to tell who's the real Queen and who's a decoy.
 * To take this trick even further, the handmaidens were often chosen for their physical resemblance to the Queen.
 * The climactic scene in Three Amigos, where the title characters emulate such a trick from one of their movies when they find out the townspeople they are trying to defend can sew. Good thing the bad guys can't shoot for anything.
 * In the film version of V for Vendetta, V uses this tactic to escape after taking over the television studio by dressing his hostages to look just like him. Later, V distributes replicas of his Guy Fawkes mask across the country, and on the eve of his climactic attack on the government, London is overrun by thousands of people in V costumes.
 * In Raiders of the Lost Ark, Indy is pursuing a pair of Egyptian men who are carrying a basket holding Marion Ravenwood. He runs into an open area filled with men, all dressed like the guys he's pursuing and carrying identical baskets.
 * In The Fugitive, Richard Kimble walks out into a Saint Patrick's Day parade in downtown Chicago, pretending to be part of the crowd.
 * Subverted in real life, because the whole crowd apparently recognized both Ford and Jones.
 * In the film version of The Saint, Simon Templar hides in plain sight from the Russian mobsters who are chasing him by putting on a homeless man's coat and hat, swigging from a bottle of vodka, and acting drunk... just like the dozen or so homeless drunks around him.
 * The climax of Sister Act where Sister Mary Clarence's fellow nuns disperse throughout a Reno casino to confuse Mary Clarence's ex-boyfriend's henchmen. However, they don't fully succeed because
 * You'd think they'd spot the only black nun in the group.
 * But they're wearing habits. If you spot one from behind, you can't tell whether she is black or white. So that tilts the odds a bit in her favor.
 * Variation in Men in Black. Whilst chasing the bug, J spots a discarded bead seat cover and realises (correctly) that the bug has hijacked a NY cab. He runs out into the street to catch him and... well... it's New York, use your imagination.
 * The end of Darkman has a scene like this, with the titular hero leaving his love interest because It's Not You, It's My Enemies and disappearing into a crowd. The effect is increased by the fact that the hero has discovered a formula which gives him the ability to temporarily assume the appearance of anyone he chooses, meaning he could literally be any of them... and whilst the love interest is looking around desperately, we see a guy we've never seen before (one of Bruce Campbell's many appearances in Sam Raimi films) looking back at her with anguish before turning and walking away...
 * Part of Kansas City Shuffle that Clive Owen's team implements in Inside Man. Everyone in the bank is (forcibly) dressed in the same outfit, making a proper SWAT Team siege impossible.
 * In one scene in The Dark Knight, dozens of hostages are dressed in clown masks, their mouths duct taped shut (so they can't indicate that they're not bad guys) and guns duct taped to their hands. The impending SWAT team doesn't see anything amiss, but fortunately Batman is smarter.
 * Also, following the initial bank robbery scene, when  gets away in a school bus and merges into a long column of school buses.
 * A funny unintentional version occurs in the movie The 51st State: Samuel L. Jackson is flying into London, and he's taken to wearing a kilt. A Corrupt Cop hoping to intercept him tells a subordinate to wait at the airport for a dark-skinned man "wearing a dress." It's the henchman's bad luck that just as Jackson arrives, so do several flights from African and Asian countries where men still wear robes, sarongs, etc....
 * Sonny, the titular character in the film version of I Robot, pulls this by hiding in the ranks of hundreds of similar models, making this a crossover with Needle in a Stack of Needles.
 * In the film version of Minority Report, Anderton and Agatha (the Precog) get out of the mall as it starts raining, and he simply holds up a black umbrella (which Agatha had insisted on grabbing) as the cops run out on the roof overhead, and look at the sea of black umbrellas. Ironically, Anderton and Agatha didn't move after putting up the umbrella, so the cops were literally right over them, and never saw them.
 * North by Northwest - as his train arrives in Chicago, Roger evades detection by the waiting police by dressing as a redcap (railroad baggage handler) - by the time the police find the real redcap onboard without his uniform (which Roger paid him for), Roger has disappeared into a sea of redcaps.

Literature

 * Harry Potter features this, with multiple Harrys created via polyjuice potions to protect the real one.
 * One of the Where's Waldo books (The Great Waldo Search) features, on the last two-page spread, Waldo standing among members of "The Waldo Fan Club"... all of whom are wearing his trademark outfit (blue trousers, red and white sweater with matching bobble hat).
 * In The Darksword Trilogy, Simkin helps Mosiah escape from the Secret Police by casting a mass illusion spell that makes an entire crowd of people look like him. The crowd doesn't even suspect Simkin of anything underhanded, since his Cloudcuckoolander credentials are already firmly established; they just think he's attempting to start a new fashion trend.
 * Done with overlap with Needle in a Stack of Needles in a short story in I, Robot: a robot with a modified First Law is told to go lose itself, so it does. In a crowd of identical-looking but non-modified robots.

Live Action TV

 * In one episode of Charmed, the sisters cast a spell that made every male everywhere look like Leo, hoping to outsmart the angel of death that way. (Of course, it doesn't work; nothing stops Death!)
 * In the Stargate SG-1 episode "Insiders", all the Ba'al clones present claim to be the real Ba'al (thus also creating an I Am Spartacus moment. (Colonel Mitchell even refers to them collectively as "Spartacus" during a Hurricane of Puns prompted by the name "Ba'al" and the word "ball").
 * Voyager's holographic Doctor has an episode where he's coerced to act against the ship (actually a few, but stay with me here). Eventually he's found out and on the run, and ducks into the holodeck. In a couple seconds, he conjures up an entire room full of... himself. A bunch of copies of his appearance. While the crew figures out how to determine which one's the real one, he's already escaped into a jeffries tube.
 * In an episode of Castle, the cops drop off the ransom in a certain bag. Then they try to take down anyone with that bag. Naturally, everyone is carrying an identical bag as a part of a 'performance art' piece.
 * Variation from Leverage: In "The Second David Job", the team plants fake David statues in everyone's bag at the museum coat check.
 * In an episode of The Mentalist, the Monster of the Week dresses up as a clown to kill their victim (who has a clown phobia) and puts out a casting call on the internet for clowns. When the CBI shows up and tries to find the killer, based on the 'clown' description, there are more clowns there than you could shake a slapstick at. Meanwhile, the killer clown has vamoosed.

Music

 * The Australia version of Linkin Park's "What I've Done" music video involves this; a scientist at a corrupt pharmaceutical company does a Heel Face Turn and steals a sample of The Virus the company is developing to control the populace, handing it to a member of what's presumably a resistance fighter in a black hoodie with the band's logo on it. When the company's agents give chase, they're cockblocked by several other people in black hoodies with the band's logo on it. In a subversion, however, the purpose of this wasn't just to delay the goons long enough to get the sample to the appropriate authorities; they goaded the goons into following them, in order to expose to the company just how large the resistance against them is and intimidating them into backing down from their schemes.

Video Games

 * Being Lost in a Crowd is a crucial part of Assassin's Creed. Not only does the end of the opening movie shows this exact thing, but in-game Altaïr can use Scholars as (who are all dressed similarly to him) as "mobile hide points." He can "blend" on his own by making a praying pose and walking slowly, but he needs the Scholars to bypass guard posts... not least because he openly carries a longsword, short blade, and throwing knives, and he needs the Scholars to block the guards' view of his weapons.
 * In Assassin's Creed II this changes up somewhat with Ezio, who can now blend into any group of four or more (sometimes three, and with Courtesans as low as two), but the Assassin Robes he wears all the time are extremely distinct, not least because he wears a Assassin emblem on the front of his belly. In Brotherhood this blending ability gets much more plausible if you choose to equip the Florentine Noble Attire (a Uplay Reward), since that outfit (his day wear from before he donned the Assassin Robes) is much more like the clothing worn by Roman civilians.
 * This can become even more ridiculous if you're using the unlockable Raiden outfit, because nothing says 'inconspicuous' like a cyborg ninja in 16th century Rome.
 * The multiplayer mode in Brotherhood runs on this; the entire world is populated with only a handful of distinct character models, and success is often a matter of finding a group of identical NPCs and trying not to act human.

Web Comics

 * In this Adventurers! strip, an evil being from Another Dimension shows up and announces, "I am looking for a large-haired hero and his friends". He really should have been more specific.

Western Animation

 * In the Avatar: The Last Airbender episode "The Headband" - after Aang throws an illicit dance party for a bunch of Fire Nation schoolchildren, the kids help him escape from some soldiers by donning their belts as headbands, as Aang had done to conceal his Airbender tattoos. Since the soldiers had been told to go after the boy wearing the headband, this created enough confusion that Aang and his friends were able to escape unnoticed.
 * This happened to the Joker twice in Batman: The Animated Series. First came when a millionaire built a casino themed after the Joker, which naturally led the Clown Prince to decide to blow it up. When the Joker showed up to do the job though, he soon found all the card dealers and much of the staff were dressed in his clothes and wearing make-up and wigs to resemble him. This not only helped him escape Batman for a little while (Bats kept chasing down Jokers to find they were just casino employees), but also let him march right up to a Blackjack table and start dealing. A later example game when he decided to set off a bomb on New Year's, he handed out Joker-Masks to the crowd so he'd be tougher to find. Didn't work so well that time, though.

Real Life

 * Embroidered jeans and overly large white tee-shirts aren't a cause of urban crime, but when half the people on any given block are wearing basically the same thing...
 * This case involves a guy who robbed an armored truck, then escaped into a crowd of people dressed exactly like him (that he had set up using Craigslist).
 * The Swedish police was put under heat when a murderer out on a day long permission (under surveillance) managed to flee by waiting until the Christmas Crowd was especially dense and then... started to run like hell.