Mistaken for Badass

The Tourist is a monster. After intercepting The Courier and stealing The Package, he's liquidated or turned every agent, assassin, and hitman sent to retrieve it or kill him. Every spy agency this side of the Atlantic are scouring their records, trying to discover who he is, what he knows and who he works for. But one question burns brightest: "What does he want?"

To find that nice local bakery that makes the chocolate croissants.

Somehow the protagonist has been Mistaken for Badass, through no merit of his own other than some well timed ducking, a little obliviousness, and a lot of incredible coincidences. He's a bumbling, perfectly normal Nice Guy that has gotten mixed up in a very real, serious, and deadly affair. Maybe he muddled his way through some Spy Speak and convinced the CIA he's the MI6 operative they sent, or somehow knocked out or killed a highly lethal assassin before they made a hit, or otherwise had the MacGuffin fall on his lap. Or he's the only survivor of that nasty mess-up he was caught in, due to inhuman level of luck, maybe not even realizing just how deadly all this was. Everyone believes the Innocent Bystander has no chance, so not only did The Tourist know what was going on, but he had also proven himself as the most competent of all the dangerous people involved. It helps a lot that there are several sides who will never sit together and add up everything they know about the case, but will watch each other just enough to overhear their rivals' suspicions and assume that the other side "knows something".

This guy manages to not just survive the attentions of those interested, but do so in a way that convinces the bad guys he's actually a Badass Normal who is Made of Iron. If someone insist he "drop the act", he'll confusedly answer he doesn't know what they're talking about, he's just Joe Average and wants them to quit trying to kill him. Of course, they conclude he's using a deep cover Crouching Moron, Hidden Badass act. Which all things considered is not that far from the truth.

This character can be mistaken for a paragon of any profession that requires a lot of training and competence, not just spies but also martial artists, cops, thieves, or what not.

In the most extreme instances of this trope, the protagonist doesn't even notice what he's doing. He may kill every assassin dispatched against him with casual obliviousness, disassemble the evil plot with trivial ease, and otherwise destroy the bad guy's evil empire without ever becoming the wiser. Sometimes, they do clue in to what's going on about half way through, but still manage to pull through.

This can be done completely straight in an action movie or drama, with the character panicking once he realizes just what he's gotten into. On the flip side, this can be amazingly funny in a comedy by using both slapstick methods of beating or killing opponents, and making fun of all these "professional" organizations out to get our hero.

The Clueless Detective may be overestimated the same way

See also Mistaken for Spies, Inspector Oblivious and And You Thought It Was a Game. Compare Seemingly-Profound Fool.

Anime and Manga

 * In Cromartie High School, Kamiyama's clean-cut appearance as well as his choice to enter a school of delinquents initially earned him a reputation as a wolf in sheep's clothing.
 * The main character of Angel Densetsu. He's so ugly that everyone mistakes him for an inhuman monster, and his social awkwardness doesn't help. His "reputation" grows to the point that gang leaders challenge him to fights all the time. Fortunately, usually Defeat Means Friendship.
 * Mx0: Through an unlikely sequence of events, Taiga starts the manga off mistaken for a genius mage capable of kicking a teacher's ass no problem, when he actually has no magic ability at all. Though in his case, it's more "Mistaken for Super" than "Mistaken for Badass", as he would never have been able to bluff/survive through the first term without being a considerable Badass Normal.
 * Sakaki of Azumanga Daioh is looked up to by fellow classmates due to her looking "cool" and "mysterious". In actuality, she's just very shy.
 * Mara Shin of Dorothy of Oz has a four million dollar price on her head for allegedly killing Selluriah, the Witch of the East. However, Mara is actually just a normal high school kid who just happened to be in the wrong place at the wrong time and got blamed for it because a hysterical soldier accused her of it after finding her standing over Selluriah's dead body and wearing her magical boots. It also doesn't help that she allows Abee and Number 50 to escape from some Eastern soldiers who want them dead for being Western spies, or that she helps wayward scientist Dr. Nedbar escape from Tick Tock with the Witch of the South's newest and deadliest creation. Or that she travels with three supposedly dangerous escaped biological experiments, all of whom are incredibly loyal to her and will lay down their own lives to protect her. The fact that she doesn't have very good control of her powers in her witch form contributes a bit to the mess as well...
 * One Piece: Most of Buggy's character arc after hitting the Grand Line. Due to his past with Gold Roger, as well as a series of coincidences and some truly desperate prisoners looking for a leader, Buggy has become something like Pirate Moses.
 * Holyland: Yuu just wants to be left alone. However, being forced to take down bullies that try to have their way with him leads to developing a reputation as a fearsome bully hunter and in turn leading more punks to fight him.
 * Furuichi in Beelzebub is somewhere between this and Action Survivor. Yes his best friend is the biggest delinquent in all Japan, but Furuichi can't fight to save his life.
 * This reputation both helps and hinders him. On the one hand, he's considered a ringleader of delinquents by many school officials and so whenever the actual delinquents do anything worth punishing, his name will at least come up, if he doesn't get punished as well. On the other hand, he's managed to unite several delinquent groups  and they really only listen to him because he had this reputation.
 * Also, being Genre Savvy, Furuichi knows that this rep is still going to bite him more than be helpful. He knows he's the Butt Monkey.
 * Seiji from Midori Days is badass but his Bromantic Foil's constant rumor mongering make it hard for Seiji to get a girlfriend.

Comic Books

 * Subverted in The Authority story "The Magnificent Kevin": the titular Kevin has this happen to him with a couple of foes. Most notably, as the story opens, two groups of opposing spec ops forces that he worked for converge on him in his bedroom. He is under the sheets looking at porno and notices none of this. The two opposing forces massacre each other while he is otherwise engaged. The funny part comes when it is mentioned that this sort of thing seems to happen to the assassins they send after him all the time, which causes the higher ups on all sides to send more assassins to kill someone who must have been superhuman to kill all the previous assassins, which results in a bigger massacre, and so on and so forth. Subverted in that "Kevin" probably would be a badass by normal human standards, just not in the Authority universe, and he isn't so much "mistaken" for badass as "employed by too many of the wrong people on both sides of the tracks."
 * Bob, Agent of HYDRA, is mistaken for badass in Cable & Deadpool when he accidentally knocks out a symbiont dinosaur that he'd been trying to run away from.
 * An Astro City story featured Mitch Goodman, a soap opera actor playing a superhero who foiled a convenience store robbery. He rode the ensuing publicity to promote his acting career, but things turn sour when he soon becomes targeted by real supervillains.
 * One from The Adventures of Tintin. In a deadly game of cat and mouse between the protagonist's ship and a submarine, Captain Haddock accidentally gets the ship stuck going astern (backwards). When this results in a torpedo barely missing the ship, the villain's marvel at the captains tactical genius.

Fan Fiction

 * Mr. Black, from the Harry Potter Fanfiction Make A Wish, written by Rorschach's Blot. Throughout the story, he somehow manages to accidentally convince everyone that he's: a veteran Magical Law Enforcer; the world's deadliest assassin; a rampaging and particularly creative psycho killer; a rare creature specialist; a master of stealth and evasion; a master of detection, ward, and deadly ancient spells; a member of various old organizations, rebellions, and militias; a vampire hunter; a noble; a sex god; a master archaeologist; at the very least, a 13000 year old immortal; the destroyer of countless civilizations; and finally Death Incarnate. He was just a regular guy on vacation.
 * Played with in Desperately Seeking Ranma by PixelWriter1. Nabiki Tendo, using disguise magic and a couple ki tricks, takes on the role of "Ms. Aoyama", an apparent alien who works for a very powerful, very secretive organization.  (She does this mostly for good reasons rather than just kicks, having grown since the end of the manga.)  The effect she has on people in this role is so profound that eventually she has entire governments wary of upsetting her or her "employers".

Films -- Animated

 * Rango spun a lot of tall tales about his alleged prowess, but when the hawk attacked Dirt, Rango's wild chase and dumb luck had the townspeople assuming he was actually fighting off something five times his size and doing a great job of it.

Films -- Live-Action

 * The Soviet comedy film Diamond Arm tells the story of The Ditz (played by the famous Soviet clown turned comic actor Yuri Nikulin) who, due to a series of coincidences, was mistaken by a smugglers' gang for a fellow smuggler, and had diamonds hidden inside a fake injury cast on his arm by them. Hilarity Ensues.
 * The basic premise of the film If Looks Could Kill.
 * Also the basic premise of North by Northwest, though he does figure it out eventually.
 * Le Grand Blond avec une Chaussure Noire (The Tall Blond Man with One Black Shoe) has The Ditz played by Pierre Richard first mistaken for a spy, then used as a decoy by the only agency that knew he isn't... and everyone's cluelessness continued into the sequel Le Retour Du Grand Blond.
 * It was remade as The Man With One Red Shoe.
 * In Le Coup du Parapluie, everyone assumed The Ditz (also Pierre Richard's) to be a top-notch hit man.
 * The Man Called Flintstone. Due to his incredible resemblance to superspy Rock Slag, Fred Flintstone is recruited by Slag's boss to impersonate him when he's injured. Fred manages to convince the Big Bad the Green Goose that he's Slag, which is a problem as the Goose wants Slag dead.
 * The Man Who Knew Too Little
 * Saw. "Mistaken for a hitman" variant.
 * Subverted in Lucky Number Slevin ...and that's enough about that.
 * Probably the entire point of The Pink Panther, less so in the remake since Drefas manages to finally get through to him and he has that whole self-doubt part before he gets back into action. Peter Sellers's Clouseau would never have caught on to that.
 * Of course, he was just another character, rather than the star, of the first Pink Panther movie, so maybe not that one so much. A Shot in the Dark plays it perfectly, though.
 * Another "mistaken for a hitman" variant occurs in the original El Mariachi, which has the title character, a musician, mistaken for an assassin who carries a guitar case full of weapons who is out to kill the local drug lord.
 * The Man, with Samuel L. Jackson and Eugene Levy.
 * A major plot point in the western The Man Who Shot Liberty Valance. Tenderfoot lawyer Ransom Stoddard kills the notorious outlaw Liberty in a gunfight, making him a local hero.
 * The Stupids features an entire family like this foiling an arms deal between corrupt military officials of multiple nations. The family patriarch Stanley Stupid alone manages to inadvertently defeat at least three assassins.
 * A plot driver in Carry On Cleo where the escaped slave Hengist Pod is concussed hiding under a table while his badass neighbor, Horsa, takes out a squad of legionnaires and makes good his escape. With all the witnesses dead the authorities assume Hengist is the badass swordsman and he is made personal bodyguard to Julius Cesar... Hilarity ensues.
 * Another example in Carry On Cowboy when a stagecoach carrying Marshal P. Knutt and a young woman is attacked by outlaws. He shoots wildly while she kills them all and then lets everyone, including Marshal (yes, that's his name) believe he did it. He is mistaken for a lawman because of his name (he actually fixes drains) and is recruited to deal with a problem that some "rats" are giving the town.
 * Three Amigos: The entire plot is based on this. Three actors are mistaken for actual heroes and somehow manage to beat the bad guys.
 * The 1968 Disney movie Never a Dull Moment starring Dick van Dyke. This one used the "mistaken for hitman" version.
 * Killer, a Polish comedy, is about an innocent taxi driver named Jerzy Kiler, mistakenly arrested as a professional hitman, then sprung out by a mobster who needs his services. Deciding he needs to play his part until he can clear his name and outsmart the mobster, Jerzy looks for inspiration by renting movies like Léon: The Professional, Taxi Driver, Psy and others. Hilarity Ensues.
 * A lot of Danny Kaye movies involve this, especially The Kid from Brooklyn, where a milkman is mistaken for a prizefighter, right down to the well-timed ducking slapstick.
 * The protagonists of Dumb and Dumber.
 * Galaxy Quest: Actors in a Star Trek Expy are mistaken for their characters.
 * The In-Laws.
 * The protagonists in Tropic Thunder were mistaken for real soldiers by the drug lord. It didn't help that Tugg played with a real severed head and made the onlookers think he has no fear of death.
 * Amazingly, they manage to take on said drug lord in multiple skirmishes while firing blanks.
 * Pretty much the entire plot of the Chris Farley movie Beverly Hills Ninja.

Literature

 * Brazilian writer Luis Fernando Verissimo wrote a short story about a loser who ends up kidnapped by some thugs who mistake him for a Mafia boss and plan to kill him. He eventually reasons that it was more thrilling than anything that ever happened in his life, and asks for some champagne (something he had never tasted) before getting murdered.
 * The novel Pest Control has Bob the Exterminator, an elite international assassin. Only he's just an environmentalist bug exterminator looking into symbiotic methods for pest control, and the people he "killed" really did die in a series of coincidental and unrelated accidents. The only way he managed to survive was due to luck, help from an actual international assassin named Klauss, and thorough knowledge of New York's heavily armed crazy people that are no danger unless provoked.
 * In A Night in the Lonesome October by Roger Zelazny, a bunch of magic-users preparing for the imminent ritual confrontation mistook one bystander—though not exactly "innocent"—for a participant. Massive scheming ensued. They (or at least their familiars) learned he never was in their game too late for it to matter.
 * One of the protagonists of a detective comedy series by Leo Gursky is The Chew Toy, a poor henpecked Absent-Minded Professor pharmacologist so modest, naive, painfully honest and law-abiding (and, well, absent-minded) that once he's entangled in something, most strangers refuse to believe he can really be this much of The Ditz. Once he stumbled upon a Briefcase Full of Money and tried to return it to the rightful owner . Another time he picked up ringing "discarded" cellphone.
 * Lenny in The Stingray Shuffle drives erratically because he is high on marijuana. The ex-KGB agents following him mistake his driving for elite evasion techniques, and assume he must he former CIA or Mossad.
 * "The Brave Little Tailor". "Seven in one blow!"
 * Ciaphas Cain, anyone?
 * Or so he claims... He actually shows distinctly badass qualities throughout, including dueling various Super Soldiers, aliens and daemons successfully.
 * This is actually averted. Ciaphas is one of the best swordsman and pistol shots in the Imperial Guard because he practices obsessively, even by Imperium standards. It's one of the few instances where Ciaphas actually acknowledges his own abilities. He still claims a lot of his survival is luck, but he does have the physical abilities to back that up.
 * Harry Flashman in the Flashman novels by George Macdonald Fraser. Although many characters met by the protagonist know him (or come to know him) to be a cad and a coward, his reputation among society at large is that of a brave and honorable man.
 * Flashman lives for this trope. He can run away from a battle and hide in a cesspool, then show up weeks later and be hailed as a hero for being the lone survivor. He encourages this sort of thing, but all he really has to do most of the time is keep his mouth shut.
 * Rincewind of Discworld ends up like this in Interesting Times, thanks in part to being Shrouded in Myth due to a book based on his misadventures written by Twoflower from the first two books, but also because of his strange tendency to survive otherwise fatal situations. People think it's because Rincewind is some kind of powerful and wise wizard, but it's mostly a combination of being favored by The Lady and his own attempts to remain a breathing coward.
 * The Dorothy of Oz example above was cribbed from The Wonderful Wizard of Oz where the Munchkins assumed that Dorothy must have been an insanely powerful Munchkin sorceress to call up a storm and squish the East Witch with her house. Compounding this misunderstanding was that Dorothy was the size of a adult Munchkin and wearing her blue and white gingham dress. In Oz, Munchkins favor blue, and only magic users wear white. That's why they called the North Witch for help.
 * Invoked by Rand in The Wheel of Time: Tam gave him a heron-marked sword at be beginning of his adventures, but he had next-to-no training. Throughout the first book pretty much everyone he met openly doubted that someone so young could be a blademaster, but troublemakers didn't want to risk being wrong.
 * It is also averted when in less than a year
 * A common theme in Tom Sharpe novels, especially some of the Wilt series in which Wilt comes to the attention of the police who investigate him, find nothing but are sure they're missing something so investigate the entirely innocent school teacher more and more urgently until they eventually make a career-ruining mistake which they blame on Wilt outsmarting them rather than themselves getting obsessed over nothing.
 * Don Quixote, USA has the narrator/protagonist a Peace Corps Volunteer trying to help the insurgents on a Caribbean island. He accidentally sabotages their operations so thoroughly that a Soviet agent, looking into whether it'd be worth Moscow's while to fund them, concludes, "At last I meet an American agent who makes no errors. My compliments." The American, meanwhile, thought the Russian was a Swiss banker.

Live-Action TV

 * A huge part of the premise of Chuck.
 * This looks like it's what's going on in the Monty Python's Flying Circus "dentistry sketch" until the very end, where the character reveals that he actually was a dentist.
 * An episode of Monk has him going undercover as a famous hitman. In a meeting with a mobster, he leans over to straighten one of the henchman's ties and everyone reacts like he's making a threat. Of course, Monk being Monk, he really did just want to straighten out the tie.
 * Burn Notice did an episode about a doctor being harassed by a drug dealer so Michael and crew make it look like he's ex-Special Forces.
 * This looks like it's what's going on in the Monty Python's Flying Circus "dentistry sketch" until the very end, where the character reveals that he actually was a dentist.
 * An episode of Monk has him going undercover as a famous hitman. In a meeting with a mobster, he leans over to straighten one of the henchman's ties and everyone reacts like he's making a threat. Of course, Monk being Monk, he really did just want to straighten out the tie.
 * Burn Notice did an episode about a doctor being harassed by a drug dealer so Michael and crew make it look like he's ex-Special Forces.

Theater

 * Nikolai Gogol's comedy play The Government Inspector starts this way, with a poor but foppish gentleman visiting a small town and ending up mistaken for a government inspector by the local obstructive bureaucrats. He quickly understands what's going on, and uses the situation to swindle a neat sum out of the locals. Then he leaves and the real McCoy comes...

Webcomics
"Violetta: You've trained in the way of smoke?"
 * Fat Pony is mistaken for a hitman, and a successful hitman at that, despite being nothing more than a pony.
 * Girl Genius has Moloch von Zinzer, veteran armor crewman and Action Survivor. The results of his devotion to the cause of "not being killed" were taken as evidence of some secret knowledge:

Western Animation

 * DuckTales had an episode where Launchpad was recruited to fill-in for an injured spy. In fact, some of the elements that appeared in this episode later were used in Darkwing Duck
 * Launchpad is mistaken for the real Darkwing after a "Darkwing Decoy" plan backfires and he is caught unmasking by the press. Darkwing, thanks to his massive ego, is not pleased with Launchpad's new found fame.
 * There was a Rocky and Bullwinkle story which involved a laundry and Bullwinkle accidentally saying some long complicated code phrase that would only be said accidentally in a comedy. I'm sure someone else remembers the details.
 * That's from Bullwinkle's Testimonial Dinner. What happened was that Bullwinkle sent his shirt to be cleaned at a Chinese laundry in Shanghai. Said laundry was being used by Boris and Natasha as a transfer point to smuggle an atomic bomb wristwatch. The man who was supposed to pick it up was to identify himself by saying, "Perhaps you would rather I be John Phillip Sousa." Bullwinkle ends up saying that exact phrase when the clerk remarks that he's got a funny name.
 * The Simpsons: Homer becomes an unwitting Mook to Hank Scorpio in one episode.
 * He did, in fact, tackle a "loafer" whilst working for Scorpio.
 * In fact, this happens to Homer multiple times. In an early episode, he gripes about conditions at the power plant and is appointed, as the new union leader, to negotiate for the workers to Mr. Burns while they strike. Mr. Burns thinks Homer a "worthy opponent" until he offers Homer a generous deal to step down as leader, and Homer celebrates by imitating one of The Three Stooges in Mr. Burns' office.
 * Sid the Squid, a bottom level criminal Mook in Batman: The Animated Series was credited with offing Batman because they saw him knock Batman into a fuel tank which exploded. Lots of people wanted a piece of the guy that took out Batman, while The Joker was furious that some no talent nobody took out Gotham's number one vigilante..
 * And even then he benefits at the end when
 * Duck Dodgers is a poster boy for this trope, though he is occasionally competent.
 * In the Star Wars: The Clone Wars episode Bombad Jedi, Jar Jar Binks is mistaken for a Jedi in a Separatist-occupied city because he slipped which led to him dodging an attack and he was wearing a cloak. The guards were none too bright. Hilarity (and heroism) ensues.
 * This helped decrease his Scrappy-ness since he instantly realized that they thought he was a Jedi and ran with it, instead of doing everything completely by accident like in the films. He was clearly trying to channel Obi-Wan with his acting.