Underestimating Badassery

"Billy Jack: I'm gonna take this right foot, and I'm gonna whop you on that side of your face... and you wanna know something? There's not a damn thing you're gonna be able to do about it.

Mr. Posner: (sarcastically) Really.

Billy Jack: (nodding) Really. (does exactly what he promised)"

- Billy Jack

We all know just how awesome the Badass is, whether they look the part or not. Unfortunately, not everyone else in the film or TV show does, even when the former is the case.

So maybe our hero walks into a bar, where some of the regulars don't take too kindly to him. Or maybe a couple of thugs accost him on the street. Sure, he might look dangerous, but he's outnumbered and outgunned, so he shouldn't be a problem, right?

The viewers watch with bated breath for the moment that these guys find out that they've woefully underestimated the level of badassery involved.

Compare Beware the Nice Ones, Good Is Not Nice, The So-Called Coward, Mugging the Monster, Dude, Where's My Respect?. Contrast with Bullying a Dragon, where the perpetrator antagonizes someone despite knowing full and well how Badass they are.

Anime & Manga
""You made the mistake of thinking of me as a mere powerless girl, Mr. Mage.""
 * In Fullmetal Alchemist, Edward Elric is often underestimated due to his height. Bad idea.
 * Tengen Toppa Gurren Lagann: Because Simon is a skinny young kid, no one (except Kamina) ever respects him as much as they respected his muscular older bro, even though Simon is and always has been infinitely more powerful than Kamina.
 * In One Piece, this often happens with the villains (or even minor assholes) when they first meet Straw Hat Luffy. It doesn't help that he's a skinny, idiotic 17-year-old that makes a habit of boasting that he's going to be King of the Pirates. They soon learn to wise up after he comes back for round two!
 * At Water 7, Zoro is left in charge of the ship while everyone else goes shopping. A group of bounty hunters try to take him out, thinking him asleep and outnumbered, therefore, outmatched. The first two are true; the third, not so much.
 * In Darker Than Black: Ryuusei no Gemini, Section 3 underestimates Hei after they De-Power him, and Genma thinks that he's "just a gloomy gigolo." But remember that this guy was called "Black Reaper" before he became a Contractor. Somewhat justified in that prior to Hei's He's Back moment solidified in this episode, Genma had pummeled him fairly easily in an earlier fight, although the ability of Hei to survive a beating from a psycho with Instant Armor power is itself impressive.
 * It's not the only time, either. Witness the woefully-overconfident assassin teams sent to kill him during the interquels; you'd think that nickname would be a bit of a tip-off, but this is apparently not the case.
 * In Mahou Sensei Negima, upon arriving in a Magic world bar Negi is attacked by a random thug because he resembles a guy who beat him sorry many years ago - actually Negi's infamous father "The Thousand Master". In retrospect that should got him thinking...
 * For the record, that "random thug" is Vargas, one of the baddest guys in town, and pretty everyone who's not Negi (or Kotaro, or Chachamaru, who were with him) would do well not to underestimate him. More importantly, Vargas, his little brother Tohsaka, and their mother become plot-relevant Mauve Shirts later.
 * Interestingly enough,  pulls this on the one of Fate's associates.


 * Anyone who ever thought that fighting Jack "Thousand Blades" Rakan is a good idea. Like Fate's minions believing they could take him on a 4 on 1 fight. He's the personification of awesome for a reason, people.
 * Durarara's Shizuo Heiwajima, Ikebukuro's resident God of Destruction, doesn't particularly look like the sort of person who would (or even could) uproot vending machines and beat people half to death with them when he's not actively doing so. Thus, many people don't realize that it's a bad idea to pick a fight with the skinny guy in a bartender suit until it's far too late.
 * Many groups in Ichiban Ushiro no Dai Maou seem to have Akuto in the sights of their manipulations, and casually talk about pushing him aside or disposing of him or some such, which would be incredibly stupid considering his "Demon Lord" status. And this isn't even getting into those dumb thugs that tried to pick a fight with him and instead ended up with broken limbs.
 * The title character of SWOT, Manabizaki, is a bespectacled nerd who studies too much. He has a Hair-Trigger Temper and a tendency to mouth off to people. Naturally, every delinquent in school was practically lining up to beat the crap out of him and put him in his place. After all, he's just an overly-studious nerd, ain't he? They're always weaklings, right?
 * North Italy/Feliciano in Axis Powers Hetalia. This could arguably apply as well to Austria and Finland, given their histories.
 * The Thompson sisters in Soul Eater make this mistake regarding the skinny boy in the suit who comes looking for them. It's also noted in canon by Maka that Kid looks so 'low-key' and unimpressive that it's easy to forget he's a death god and so a very formidable opponent when he feels like it. His eccentric behaviour only enhances that impression. A similar claim could be made about his father Shinigami, although all who have encountered him so far know what they're dealing with and are appropriately wary.
 * A serial occurrence in Naruto (indeed, in a lot of shonen) due to a combination of this trope and Just a Kid. The amount of times a villain has smack-talked one of the heroes...
 * Characters underestimating Naruto more often comes because they simply knew him as a struggling ninja academy student, post time skip, it became less common, especially since he started win enough fights that would more liken make other afraid to take him on.
 * Kabuto is a repeat offender, even when, by all rights, experience should have taught him better. Then again, he is Smug Super and a colossal Jerkass.
 * A lot of antagonists from Pumpkin Scissors think War Relief Section III is a group of incompetent idealists. They are quickly proven wrong when War Relief Section III manages to derail villains' plan all by themselves. Especially applies to Randel, a Super Soldier who can stop tanks on foot.
 * Several characters made the mistake of underestimating a certain blonde haired gentleman by the name of Johan Liebert.
 * Misaka Mikoto from To Aru Majutsu no Index is the third strongest esper in academy city, and everyone knows about her, yet for some reason delinquents frequently try to hit on her, generally resulting in them getting electrocuted. In fact, in the first scene of the first episode of the anime the main character is running from delinquents that he got to chase him because they approached her carelessly. in the end, she still zapped them.
 * The current Big Bad Duumvirate of Bleach made a big, big mistake of underestimating Ichigo.
 * Actually their plan to beat him, which had one of them get the jump on him and take his powers, worked just as they planned it. Though the other one still had problems since Ichigo was much stronger than him and only ended surviving because of said plan, and because he had Ichigo's friends helping him. Afterwords, a Big Damn Heroes moment caused Ichigo to get all of his old powers back.
 * Rurouni Kenshin has two varieties of people underestimating Kenshin. One, they know about his reputation that earned him the nickname Hitokiri Battousai (roughly translates as 'God-like drawn sword' the manslayer) and try to fight him anyways, or they take his refusal to kill as a weakness. Either way, the results for them prove very painful.
 * A lot of people in Berserk tends to underestimate Guts. Some of them just don't buy somebody can actually swing that ridiculously large sword of his, while the Apostles refuses to acknowledge that a mere human can kill or even defeat them, despite knowing very well that he fought countless other Apostles, killed them and lived to kill others.
 * This tends to happen to Nanashi in Sword of the Stranger, since most of his enemies don't expect some random guy, armed only with a sword that he can't unsheath, to be able to kill several simultaneously attacking samurai. Which he does. Multiple times.
 * Firo Prochainezo from Baccano is one of the Martillo family's top fighters, second only to Ronnie . He also a small, baby-faced prettyboy that looks so harmless that children think they can take him on without much trouble. Czeslaw finds this amusing.
 * A lot of vampires sent to defeat Alucard in the earlier chapters of Hellsing (mainly Luke Valentine and Allambra) have the bad habit, while perfectly aware of his reputation, of thinking of him as a simple very powerful vampire and believing they can take care of him easily. This usually lead them to a gruesome and horrible death when finding out Alucard is actually a Humanoid Abomination at his weakest, and will turn into an Eldritch Abomination if he happens to take the fight seriously.
 * Similarly, Zorin, despite being warned by the Major that Integra and Seras Victoria weren't to be underestimated, disobey orders and attacked the Hellsing mansion, assuming it was helpless without Alucard around. She ends up killing and insulting Seras Love Interest, leading her to evolve into an actual vampire and granting her a death that would have made Alucard proud.

Comics
"Tony: [to his kidnapper] I was just wondering, does your guard here know what a clavicle is?
 * This happens a few times in Watchmen, especially a number of times with Rorschach: attacked by bullies when he was a kid, when he and Nite Owl hunt for info in a bar, when he's attacked in prison…
 * This is why Apollo and Midnighter lose to Captain Atom in Captain Atom: Armageddon. The pair think Atom is just another super-powered mook, not realizing that Atom is more powerful than all the members of The Authority combined, including Jenny Quantum. The only reason they last as long as they did is that Cap refuses to go all out against people he barely knows, even ones who are currently trying very hard to kill him.
 * Countless Super Villains: Batman's just a guy in a costume.
 * And a few super heroes think The Joker's just a clown with too much free time.
 * Psh, Robin's just some Tagalong Kid Sidekick. And Nightwing's just a pretty boy in spandex.
 * In the fourth and final issue of the JLA-Avengers crossover, the supervillain Prometheus, who can pretty much download any fighting capabilities he wants, confronts Captain America (comics) and says, "I've just uploaded Batman's fighting skills. That'll be more than enough to defeat you." Cap replies, "Oh?" On the next page, Cap is seen hitting Prometheus hard enough to break his helmet.
 * To be fair, it would have been an even fight, but remember that they would have beaten the crap out of each other.
 * Happens to Spider-Man quite frequently. He's a lithe guy who swings around a lot, wears silly pajamas, and makes stupid jokes. New villains tend to forget that he's held his own with the Avengers, the X-Men, and fought just about every villain in the Marvel Universe.
 * Has happened a few times to Tony Stark, whether because his identity was still secret and therefore it's assumed that he's just a rich playboy who needs a bodyguard to protect him, or because it's assumed that he's helpless without his armor. The thing is, it's generally a bad idea to attack someone who's been taking lessons from Captain America (comics) for about a decade unless you're a professional, considering Tony once beat the crap out of a bunch of Skrulls who were pretending to be The Avengers, and he did so with his bare hands while naked and while his heart was slowly giving out. And then there is, of course, this immortal exchange:

Guard: Huh?

Tony: [karate chop] Surprise! It's what I just broke!"

"King Mob: [after taking the unlucky local firmly in hand] I'm telling you you're in the wrong film, Fatboy. You're not in the cowboy film you thought you were in. This is a different kind of movie. And you're in the scene where the redneck shitkicker picks on the stranger in town, only it's Big Arnie or a gang of vampires. I'll bet you've seen that a million times, Cowboy."
 * X-23 gets sexually harassed pretty regularly. Yes that X-23. Of course, she appears to be a normal and quite attractive teenage girl but still...
 * In Volume 2 of The Invisibles, a stereotypical redneck learns the hard way not to insult a sexy transvestite and then go pick a fight with her bald associate...


 * In The Hard Goodbye arc of Sin City, the bouncer for Katie's Bar throws out a customer, looks at Marv and tells him to leave. Marv calmly grabs his face, breaks his nose and goes in. The rest of the staff apologizes for the bouncer.
 * That entire story is set up by the fact that the all-powerful Roarks thought it would be a piece of cake to frame a murder on a big, ugly drunk, unaware that he was extremely dangerous.
 * Most people of Alysia in the first books of Les Legendaires mainly remember the Legendaries as a bunch of failed heroes who caused the infamous Jovenia Incident that turned everyone into a child when trying to save the world. As such, in the first books, their name wasn't even impressive to anyone, to the point two thugs are shown laughing when they introduce themselves. What those people tend to forget is that the Legendaries also foiled several times the plans of amuch feared Sorcerous Overlord with a massive body count, and actually succeeded in defeating said Sorcerous Overlord. They fortunately get their respect back after the Anathos Cycle.

Fan Works

 * In the Firefly fanfic Forward, this happens multiple times. The badguys repeatedly underestimate the crew in general and River and Jayne in particular, assuming the former is just a small teenage girl and the latter is just dumb muscle. In the "Last Man" story, the Six Rifles especially underestimate just how resourceful a young Jayne Cobb is when they take a contract to kill the robbery crew he was on.
 * The four, who mostly look normal and wimpy, take advantage of being underestimated whenever possible in With Strings Attached. In fact, they win the day because the skahs (and Jeft, for that matter) cannot conceive of them being competent, especially after George and Ringo are depowered.
 * Ultimate Sleepwalker: The New Dreams features Psycho for Hire Bullseye, who brags about being an A-list supervillain and mocks the supposedly C-list 8-Ball when they end up fighting during a Mob War.

Films -- Live Action
""No, Lieutenant, your men are already dead.""
 * Billy Jack - see quote at top of page.
 * The cantina scene in the first Star Wars. A couple of criminals don't take too kindly to Luke Skywalker, and probably don't think the old guy with him would be much help in a fight. A few seconds later someone's lost an arm.
 * Jabba the Hutt survived the Republic. He survived the Clone Wars. He was surviving the Empire. The Rebellion and Luke Skywalker probably seemed small potatoes compared to them. He was wrong.
 * In The Rundown, The Rock plays a "retrieval expert", and in the opening scene a client has sent him to collect a debt from a professional football player. Having approached the player in a club, he gets a drink thrown in his face before looking round to see that half the team has surrounded him. Sighing, he explains that they can do this the easy way or the hard way -- they choose the hard way. Cue one guy beating up seven or eight huge athletes with ease.
 * In Shaolin Soccer, Mighty Steel Leg is beaten up in a bar because he's not allowed to fight back. The same thugs meet him on the street and throw insults. One of them throws a football at him, he kicks it back HARD.
 * Terminator 2: Judgment Day. The T-800 walks into a bar in the buff, tells some punk to give him his clothes and his motorcycle. The punk starts a fight. Guess what happens?
 * The biker punks of the original Terminator learned the hard way that they were Too Dumb to Live when he wanted clothes. They're lucky that the Terminator in question just let them live.
 * Well, mostly.
 * The Zatoichi series in Japan lives on the basis that people are always underestimating Zatoichi because he is blind, but is really an extremely deadly swordsman.
 * The kidnappers in Big Jake assume, just like everybody else in the movie, that Jacob McCandles (grandfather of the boy they kidnap) is dead. Naturally, it never occurs to them that he might be the one coming after them. Had they known, it is very likely that they would have chosen to kidnap somebody else's grandson.
 * The head kidnapper (Richard Boone) can tell that the man following them is a Badass, and says as much; what he doesn't know is just how much of a badass he is, or how personally invested he is in the outcome of the situation.
 * Under Siege: Casey Ryback? Yeah, he's just a cook
 * Secondhand Lions: When Hub is harassed by a group of ne'er-do-well greasers in a tavern, he not only kicks their asses (FOUR to ONE, I might add) but takes them home with him and teaches them what it means to be a man. Bad. Ass.
 * In Ip Man 2, the friends of Wong Leung who he calls to challenge Ip think he looks like a laundryman, while one of the Hong Kong masters thinks his name sounds lame. They have no idea.
 * The opening scene of The Matrix has this with the cops ignoring the Agents' orders and trying to apprehend Trinity themselves.

"Tang Von Soong (referring to String, who is perhaps the world's best combat pilot): "Fortunately such people have little stomach for the nature of war"."
 * This happens to Frank Martin a lot in The Transporter movies. No one seems to expect a chauffeur to be a Badass. Frank and Lai do it to The Dragon in the first film, whom they believe to be a sleazy Amoral Attorney, and not the Blood Knight he really is.
 * Captain America in Captain America: The First Avenger, shortly after becoming a super soldier, thanks in part to, he was pretty much placed onto a USO entertainment group seeing how they don't really have much of a use for the supersoldier program. When entertaining American troops in Italy, the soldiers were not impressed with his performance (one of the soldiers was also implied to have mooned him, and they eventually pelt tomatoes at him while demanding for the girls to return). Of course, after he singlehandedly rescued 400 soldiers in one of Schmidt's bases, they began to realize just how much of a force that they should reckon.
 * Happens surprisingly often within Airwolf. Of course, most people don't count on a helicopter being more well-armored than a tank, being capable of flying at speeds up to Mach 2.5, flying into the stratosphere, and carrying enough firepower to wipe a small country off the face of the earth...

"Hancock: If you don't move, your head is going up his ass. Y'all fellas sure you wanna tabletop train?
 * Also happened with Robert Winchester, who was able to give String a run for his money in the Airwolf Simulator. The Firm restricted his roll from potential Airwolf pilot to scientist because he didn't quite have the same "natural talent" for flying that String had.
 * When the title character of Hancock is serving time in prison, he is accosted by some thugs he'd gotten thrown in there. They attempt to threaten him, apparently forgetting that Hancock is a superhero on par with Superman, but with none of his sense of fair play or justice.

Matrix: Choo choo, asshole..."

"Mo: You know what this young man said? We ain't got no legs! Dat means, I ain't got no legs, you ain't got no legs, and dem men in there ain't got no legs! Now what's dat sound like to you? Sandman: A challenge!"
 * Tap (1988): "But since you ain't got no legs..."


 * And the rest of the gang comes storming in to show Max a thing or two.

Literature
"Attolia: Euginides:"
 * This happens a couple of times in The Queen's Thief series. In The King of Attolia, Eugenides  People always forget that he had two grandfathers.
 * This often happens to Eugenides, most notably when he manages to single-handedly destroy

"Carrot(As Angua is taken into a bar): Try not to hurt anyone. Thug: As long as you do what we say, she'll be fine. Carrot: Sorry, was I talking to you?"
 * He even lampshades it:
 * It's not a real fight, but in Wraith Squadron, the Wraiths ask Wes who the greatest pilot alive is, and Wes considers for a bit, then says it's their commanding officer, Wedge Antilles, because of his killcount and time in active service. Falynn Sandskimmer scoffs at this, says that he might have been good in the past but got old and became washed up. Wedge tolerates this for a bit, then challenges her to a race in ore haulers and wins handily after toying with her a bit.
 * How does he win? Amongst other things, he drops his ore hauler on top of hers, pushes off hers, and plops down right at the finish line. The only thing she can say? "You cheated." Of course, teaching Wraith Squadron to cheat might have been an example of Gone Horribly Right…
 * Also not a direct fight, but in several of Wedge's appearances in the New Jedi Order and later Legacy of the Force, people underestimate his abilities in all kinds of things. Not piloting, but things like the ability to tell when he's being used as a political pawn about to be sacrificed, and in general his extraordinary resourcefulness and endless skill with the Indy Ploy and, sometimes, Xanatos Speed Chess.
 * Codex Alera: Anyone who is in a fight with Tavi. Period. That "furyless freak" will hand you your ass if you get him angry.
 * Harry Potter and the Deathly Hallows:
 * Most people don't take the three main characters too seriously, either, until they start winning. Meanwhile, Neville, Luna and Ginny ran a successful resistance against Voldemort's reign for the better part of the school year.
 * In Larry Niven's Known Space setting, the Kzin first encountered humanity in the form of an unarmed colony ship from a pacifist world, carrying only a skeleton crew. Seeing easy prey, they attacked. Unfortunately, "unarmed" and "pacifist" don't add up to "harmless"...
 * Discworld: "Sure, she's wearing the uniform of the City Watch, but she's just some pretty blond. How tough can she really be? Let's take her hostage again!" Protip, criminals: Captain Angua von Uberwald is also a werewolf, and one of the toughest and most dangerous members of the City Watch.


 * Also from the Watch, almost every antagonist will eventually underestimate Vimes and/or Carrot's ability to foil any evil scheme, regardless of the odds involved.
 * Cohen the Barbarian often gets this. He is a very, very old barbarian hero, but people tend to forget that in this line of work, one needs to be very, very good at it to live to an old age.
 * Lu Tze of Discworld fame does his bit to spread rule number one: "Do not act incautiously when dealing with wizened old men." Most of the population is more than willing to go along with this rule. When he meets those few who don't, he has to educate them in why the rule is in place.
 * The Wheel of Time: Gawyn and Galad, both of whom are highly-trained swordsmen, together take on a just-recovering Mat Cauthon who is armed with only a quarterstaff. Mat wins.
 * So there's this guy. He's a tall but gangly fellow, looks perpetually unshaven, wears a big coat and walks around with a big stick and generally seems like a scruffy, weird sort, but is otherwise not really all that much of a threat. A great many people, both Muggle and supernatural, consider him to just be some freaky guy with eclectic fashion sense. Except this guy's name is Harry Blackstone Copperfield Dresden, titular character of The Dresden Files. Conjure by it at your own risk. After all, this is the man who . The supernatural types eventually start coming to realize how dangerous he is, but the Muggles? Not so much.
 * So, there's this short woman, 5 foot tall, and like the example below, about 100 pounds. Head of the Special Investigations department for at least 8 years, while most last 2 weeks. Shot a half-ton werewolf monster from point-blank range. Once killed a plant monster with a chainsaw, and hamstrung an ogre with the same. And that is only the beginning of how extremely Badass she is.
 * Ebenezer McCoy: An old Scottish redneck living on a farm in the Ozarks. Sounds relatively harmless? He's one of the most powerful wizards in the White Council, and fuck with him or his loved ones and he will
 * Thomas Raith. Drunken Bishonen playboy who doesn't seem to care about much but enjoying himself. Until you hurt someone he cares about. Then he can and will rip your arm off and beat you to death with it before you have time to blink. A surprising number of people don't quite realize what it means that even though Lord Raith habitually kills his sons, Thomas is still alive.
 * Chloe from Darkest Powers. She is five feet tall and weighs a hundred pounds, maybe. She's in decent shape, but considering her size and her lack of any real self-defense training, she's not that much of a physical threat. She can raise an army of zombies in under five minutes just by thinking about it too hard.
 * Vin from the Mistborn series is another one of those five-nothing, hundred-pound girls who's constantly overlooked and underestimated because of how unimposing she looks. She killed a Physical God, vertically bisected a man and his horse, headbutted someone in the face hard enough to reduce his head to Pink Mist, and has abused her Super Strength so much that she's essentially dependent on it to function, but also gets about three times more power out of it than anyone else. Most amusing when she's facing Koloss; they tend to get very confused while she slaughters them by the hundreds because they don't get how it's even possible for someone so little to beat someone much bigger.
 * Elend gets it too, for a different reason. He was well-known among the nobility as a head-in-the-clouds-idealistic scholar with little practical experience with the outside world. Not all of them have gotten the memo that things are a bit different now.
 * Sienkiewicz Trilogy has glorious eample at the begining of the secong book. The protagonist, Andrzej Kmicic, mocks his opponent, Michał Wołodyjowski, before their duel. What happens next is such one sided fight that Kmicic ends up begging his opponent to just kill him already and spare him more humilation.
 * Rather amusingly, Honor Harrington. Oh, sure, her opponent might recognize her as a lethal opponent when in command of a starship, but surely when it comes to getting down and dirty on a personal level she can't possibly be that dangerous...
 * ...except for the time she engaged in a duel with a professional duelist (who'd been hired to kill her in the duel) and killed him firing from the hip before he could even aim...
 * ...and then killed the person who hired him in another duel, after having been shot by him in the back...
 * ...and in the next book gutted and decapitated a trained swordsmen in one movement after having only spent a few months learning the sword...
 * ...and in the next book cold-bloodedly gunning down some pirates with an antique weapon...
 * ...and everyone in the universe suddenly became Genre Savvy and now want absolutely nothing to do with Honor Harrington if it might involve a face-to-face fight.
 * Ranger's Apprentice: Halt is rather short, wears a mottled cloak, rides a shaggy pony, and has unevenly cut, greying hair. Underestimate him at your own risk.
 * In the backstory of Empire of the Ants, the whole ant population of France severely underestimated the Dwarve Ants, believing them to merely be small, weaker ants. In the following days, they took over Black Ants, Red Ants, Wasps, Termites... When the protagonists Red Wood Ants finally confront them, they discovered to their horror the Dwarve Ants had several queens in each of their colony, making them dangerous Zerg Rush specialists, and possessed hight intelligence for the specie. By the time the story has started, the two species has become nemesis to each other.

Live Action TV
"Cordelia: You don't know who he is, do you? Oh, boy, you're about to get your ass kicked!"
 * Invoked on the first episode of Angel:

"VAMPIRE: *moving towards Buffy* I don't mind a little appetizer... BUFFY: You ever heard the expression, "biting off more than you can chew"? Okay... um, how about the expression, "Vampire Slayer"? VAMPIRE: What the Hell are you talking about?
 * And in the season 5 finale of Buffy, right after a "Previously On..." summing up the entire series to date:

BUFFY: Wow! Never heard that one? Okay, how about, "Oh God, my leg, my leg?" *breaks his leg*

VAMPIRE: Oh God, my leg! Ah!"

"Marcus: Because if you don't, in five minutes, I'll be the only one at this table still standing. (they all laugh) Five minutes after that, I'll be the only one in this room still standing. (they all stand up and glower over him; cut to commercial)"
 * The basic premise of the franchise is to make the 90-pound cheerleader that the monster corners in an alley capable of ripping its arm off.
 * Multiple times on Burn Notice, especially in "Rough Seas", when Michael poses as a nervous nerd with an inhaler... only to turn on the group of drug dealers he's infiltrated when they least expect it. Also notable is "Bad Breaks", in which a bank robber has the bad luck to rob a bank with both Michael and Agent Jason Bly inside.
 * He's had it done on him once or twice;
 * Babylon 5 episode "Ceremonies of Light and Dark". Marcus the Ranger is looking for information on some crooks who have kidnapped his friend Delenn. He joins a poker game at a tough bar in down-below and asks his contacts in the criminal underworld if they have any information to share. They decline, and ask why they should help him with this.

"Marcus: You see? You can get more with a kind word and a 2x4 than you can with just a kind word. Please, continue."
 * When we come back from commercial, Marcus is holding the beaten and bloodied last person from the entire room of thugs who isn't quite unconscious yet, who is quickly blubbering out that he doesn't know anything anyways, before collapsing into unconsciousness. An exasperated Marcus complains to no-one in particular, "Bugger! Now I have to wait for someone to wake up!" He then is surprised when someone else comes into the bar: Lennier, the mousy, quiet, inoffensive diplomatic aide to the kidnapped Delenn. When Marcus grabs Lennier during their discussion, Lennier picks him up by the neck and calmly reminds Marcus not to underestimate him. Marcus, who has just kicked the crap out of several dozen criminal thugs and assorted underworld hard-cases, thus proving his badassitude beyond doubt, is forced to back down--to another character whose badassitude is perhaps even more underestimated. (Of course, a few moments later another thug finally wakes up, and out of fear, gives Marcus the information he wanted.)

"O'Neill: This [Jaffa staff weapon] is a weapon of terror; it's made to intimidate the enemy. This [Earth P90] is a weapon of war; it's made to kill your enemy."
 * As might be expected from the above example, Lennier is also prone to this. During the first season, his fighting skill is a surprise to the audience, but once it's established, he continues to use it to surprise other characters.
 * On one episode of Magnum, P.I., a Chinese assassin is asking a big hairy sailor where the MacGuffin is hidden. The Chinese assassin is an insignificant looking fellow with glasses. But when the bargaining becomes heated, the assassin kills the sailor with his bare hands in half a second and isn't even breathing hard.
 * In another episode, Higgins goes off to an island on a camping trip with some boys from juvenile in a rehab program. They mutiny, but find out that Higgins is a Retired Badass.
 * Chuck does this a lot to enemy agents who don't know what he is - his fight scene in "Chuck Versus the Beard" is a prime example.
 * Caine on Kung Fu is always underestimated by people who end up getting their ass kicked by him.
 * Pretty much the entire point behind The Sarah Connor Chronicles' Cameron. As the show's producers pointed out, and was demonstrated throughout the series, people do not expect a slender, cute, harmless-looking girl who looks like she's not even out of her teens to be a cold, implacable and utterly lethal killing machine.
 * Happens occasionally to Dr. Daniel Jackson of Stargate SG-1. In one particular instance, someone called him a nerd while he was under the influence of a physically enhancing alien device. This device also increased aggression and impulsiveness (Dr. Jackson is not usually a hothead). It... didn't end well for said someone.
 * Also happened to Carter on occasion, due to her being an attractive woman. In particular, in the episode "The Warrior", a group of free Jaffa are disappointed by the Earth-based weapons they have been provided so O'Neill has Carter demonstrate how effective the weapons are. You can see the patronizing expressions as the Jaffa doubt both the weapons and the female's shooting abilities. Needless to say, Carter proved them wrong on both accounts.


 * How often do the bad guys of 24 think they've got enough security to protect themselves from Jack Bauer?
 * McGee of NCIS. Most people realize that being a trained Federal agent makes you dangerous. Just, how dangerous could the team computer geek be? Then he starts threatening people, and McGee is actually pretty scary when he gets angry...
 * Also, if you get any ideas about going after Abby...
 * Doctor Who. "Oh look, here comes this weirdo in stupid clothing. He couldn't possibly be that smart...how dangerous could he be?" Just... look him up.
 * Another time, a Dalek (who are supposed to be pure evil) assumes that, as a companion, the person in front of him will be compassionate and merciful. The person in question merely says, "I'm River Song. Check your records again." It then begs for mercy... three times... and it still didn't work.
 * ". " Ya think?"
 * And the Cybermen would also later discover that when he asks a question, best not push him to repeat it.
 * Daleks have underestimated companion badassery before. "Who are you calling small!?"
 * They've also been on the receiving end of this Trope before. "What're you going to, Sucker me to death?"
 * How much of a threat can a gangly, clumsy servant be? Well, quite a bit if your name is Merlin!
 * Happens a lot to Mia in Hit and Miss, as she's a trans-gender hitwoman.

Music

 * Kenny Rogers' Coward of the County - a man who took an oath to never resort to violence, comes home and discovers that three men had gang-raped his wife. He tracks them down to the bar they were drinking at. One goes to confront him and he turns right around and, as they laugh, walks back to the front door. Then he locks it so they won't be able to run away from the aggression he's been bottling up for 20 years. When he's done, not one of them is still standing.
 * He then stands there and apologises to the soul of his dead father for not being strong enough to walk away from this one.

Tabletop Games

 * In Traveller one of the main reasons the Terran Confederation defeated the Vilani Imperium was that the Vilani, at first didn't think much of Terra and effectively thought of themselves as trying to "arrest" it rather then trying to "conquer" it. They found out that Terrans were warriors.
 * Happens absurdly often in Warhammer 40000, to the point where one wonders how these individuals have managed to survive for so long considering they tend to die horribly after severely underestimating their opponent. Examples include but are definitely not limited to Imperial Guard thinking that Orks are mindless brutes, Orks thinking Imperial Guard are just skwishy humies, Space Marines thinking filthy Eldar are no match for their zeal, Eldar thinking Space Marines are foolish primitives, everyone else thinking Necrons are just machines, Necrons thinking everyone else is just defenseless food... it happens a lot, is what I'm saying.
 * The most ironic example is Ciaphas Cain, who honestly believes he's an abject coward. Except events and his own better nature keep conspiring to make him a hero. Despite his claims, he is genuinely brave on more than one occasion. At one point, he tries desperately to get back to an isolated friend who's about to be overrun, and blames it on some sort of head injury.
 * A common meta example in Vampire: The Masquerade - often, many fights are between the player characters and human gangbangers who don't know that the people in front of them can, among other things, punch through walls, take a shotgun blast to the face, outrun a high-speed train or swing a longsword with one hand. And how the players love it.
 * As a general example, NPCs have an alarming tendency to underestimate the player characters' ability to get the job done.

Video Games
"Jedore: There are three of them. THREE! Anything can be killed if you do your damn jobs!"
 * You'd be surprised how many people think they can take on Shepard and his/her Badass Crew, even after s/he is Famed in Story, in Mass Effect 2. (It never ends well for them).
 * For example, Jedore, the leader of the Blue Suns on Korlus:

"Project Guard: Shepard is tearing us apart!"
 * During the mission to track down Morinth, a pair of turian muggers are convinced Shepard is just a puny human. Beatdowns ensue.
 * During the same mission Shepard can order a turian to stop harassing an asari. If Shepard is female, the turian will even make an advance on her. No matter the gender, it ends with said turian being thrown across the room.
 * Despite knowing that Wrex, the most powerful krogan on Tuchanka, has nothing but respect for Shepard, that Shepard has the balls (regardless of gender) to headbutt a krogan chieftain to get him to shut up (a species strong enough to snap a human's neck by backhanding them), and has personally witnessed Shepard and buddies not only survive but possibly kill  on foot, something that has not been done in centuries (and the last time was by Wrex), said aforementioned chieftain still thinks he can take Shepard in a fight.
 * In the Arrival DLC, Shepard is captured and sedated by an indoctrinated scientist, who has him locked up with a small army of indoctrinated soldiers outside. This...doesn't work out.

"Garrus: Honestly? The Collectors killed you once and all it did is piss you off. I can't imagine they'll stop you this time."
 * Shepard was the last person for who knows how long to kill a Reaper. The Reapers and the Collectors still believe him/her to be just one person...
 * To be fair, the Collectors did manage to kill him/her. Not that it helped.

"Harbinger: Shepard, you have become an annoyance."
 * And Harbinger has actually acknowledged that s/he is disrupting their plans. Coming from a member of a race of ultra powerful Cthulhu-esque starships, that is SERIOUS badass cred.

"Sergeant Kylon: And people actually voluntarily attack you. Are they just stupid?"
 * Despite the Illusive Man warning Kai Leng to respect Shepard's skills, Leng ignores his advice.
 * In Dragon Age, there are only two Grey Wardens remaining. One is you, the other one is in your party. Everybody still thinks they got a chance against you. Lampshaded by a guard after witnessing you fight:


 * In the sequel, this tends to happen as well, despite the entire point of the start of the game being about increasing your reputation/infamy. You still get people thinking you're "all hype" even after you get to Act 2, wherein you've reclaimed your family's noble status and bought back your ancestral home through acts of sheer heroism - specifically delving into parts of the Deep Roads that makes everyone short of the Legion of the Dead soil their armor - and have everyone up to the Arishok respecting you... Or at least having a "growing lack of disgust" for you. The fact that anything short of an entire army is willing to stand up to you and your comrades by Act 3 is the height of foolishness.
 * In the Fable series, even after the history of superhuman exploits you have well into the game, common thugs and bandits will still voluntarily attack you. This is particularly Too Dumb to Live-ish in Fable 3, where people will attack you when you're King, despite knowing of your Badass lineage and the fact that you are the only thing capable of saving Albion from certain doom.
 * Assassin's Creed II: Likewise for Duccio de Luca picking a fight with Ezio Auditore da Firenze thirty years after Ezio publicly beat him for infidelity against Ezio's sister. The reason Duccio dares to do so? He's got a few unarmed thugs for muscle, while Ezio's alone. Veers into Too Dumb to Live though, that Ezio by now was the man who fought off the would-be killers of Lorenzo de' Medici, participated in the Forli succession conflict, killed Girolamo Savanarola, fought the Borgia family guards at the bridge to the Vatican district, and even openly took to the streets to drive Cesare Borgia from Rome… all of these incidents being in public, with witnesses, and Ezio wearing the Assassin Robes. On top of that, before this Ezio was (even after his exile from Florence) had been a recognized absentee lord of the castle-town of Monteriggioni, making him a semi-public figure.
 * Mega Man X suffers from this quite a few times. Being a centuries-old "robotic relic" who is also a Technical Pacifist, many reploids think he'd be a cinch to defeat despite the fact he's a famous Maverick Hunter. They're more than a little surprised when he destroys them.
 * The Day of Sigma OVA basically centers around Sigma vastly underestimating X.
 * Many Mega Man Zero bosses mock Zero's "Legendary Hero" status and the fact that he was out of commission for about 100 years since the Mega Man X era. How wrong they are.
 * Touhou characters never seem to realize that fighting Reimu or Marisa is a bad idea. Considering the former can make herself completely invincible at will, the latter can obliterate continents, and both of them have fought and won against some of the most horrifically powerful beings in existence, it is no wonder the string of pathetically weak individuals that keep challenging them to fights don't exactly leave unscathed.
 * The Super Mario Bros.. As Dimentio found out the hard way, Luigi is not a pushover, but the brothers working together get underestimated quite a bit... And then the villains get beaten very badly.
 * Thugs treat Nightwing, Robin, and Catwoman this way in Batman: Arkham City. After all, Catwoman's just a girl, Robin's Just a Kid, and Nightwing... wait, who the hell is Nightwing? As expected, their cavalier attitude doesn't last long.
 * A rather interesting example in Vampire: The Masquerade Bloodlines: for most of the game, all of your enemies underestimate the "newbie vampire". It's semi-subverted near the end when everyone seems to realize "holy cow, how is this days-old vampire surviving all of these suicide mission?!" By that point, half of the Elder vampires want you on their side. The other half, sadly, see you as a threat and fall back into this trope by trying to kill you.
 * In the Civilization games, the NPC leaders will often make disparaging comments such as "your army is the laughinstock of the world" if you happen to have a smaller military than they do. They tend to fail to take into account things like technological advances.
 * The Elder Scrolls V: Skyrim: No one really gives the Dragonborn the caution s/he really deserves. They generally learn their error within a few moments of hearing "FUS RO DAH!"
 * The Godfather 2: Every one of the enemy mob bosses you meet talks smack to you, with Michael himself joining in at times. Regrettably, there's no Enemy Chatter for you to get the satisfaction of hearing them take their words back as you kill them off.

Web Comics

 * Girl Genius. Gilgamesh Wulfenbach. Full. Stop.
 * Incidentally, this also happens to be his Berserk Button, making it an even bigger mistake than it usually is.
 * Gilgamesh had that trope reversed on him later on, not realizing that Vole was holding back to avoid seriously hurting the Baron's son.  The end of this fight also makes him one of the very few people who managed to scare a Jäger.
 * Yet Another Fantasy Gamer Comic: "You know what we wicked pirates do with naked tied-up women, don't you?" SMACK. "Underestimate them, apparently."
 * Tales of the Questor: Quentyn gets this a lot when he first starts out. Chances are it'll happen again; he does, after all, look like an animate plush toy...
 * As the quote on the quotes page indicates, Parson Gotti is subjected to this a lot, mainly because, coming from Earth to, well, Erf, he doesn't know anything the "perfect warlord" should know. They get enlightened. Forcibly.
 * Apparently, Rules-Lawyering is the greatest ability a warlord on Erf can possess.
 * in The Order of the Stick, Tsukiko assumed she could threaten Redcloak to his face, figuring he was the spineless wimp Xykon always treated him as. Instead,

Web Original

 * Jade Sinclair (Generator) of the Whateley Universe gets this a lot, because she's a petite, pretty teenager who looks like a ten year old Japanese girl. When she is attacked by Bloodwolf and Maggot and Killstench simultaneously, she knocks two out (breaking one's jaw) and takes out the unstoppable Bloodwolf (who can heal from any injury) by nailing him to a tree. With railroad spikes.

Western Animation
"Tai Lung: (to Shifu) Him? He's a panda. (to Po) You're a panda. What are you going do do, big guy? Sit on me?
 * Tai Lung of Kung Fu Panda REALLY underestimates Po.

Po: Don't tempt me."

"Luthor : Are you going to fight me, boy?"
 * About a minute late, Po actually does sit on him…on the stairs.
 * From Justice League Unlimited: Lex Luthor has just taken out the founding members of the Justice League and is smirking at The Flash.

"Jokerz Leader: Who do you think you're talking to, old man? We're the Jokerz. Bruce Wayne: (Dryly) Sure you are."
 * ...Cue one of the greatest Crowning Moments Of Awesome of the whole show.
 * Also from the DCAU, just about every time elderly Bruce Wayne does this all the frickin' time on Batman Beyond. Proof? Go to the Batman Beyond CMOA page and find all of the Old Bruce Entries. 99.9% of those are this. the other .1% is Ass Kicking Ensues resulting from this trope.

"Payback: You're a mean old man, you know that? Bruce: Mm-hmm. And what are you? Payback: I'm your worst nightmare! Bruce: You have no idea what my nightmares are like."


 * This is one of the primary themes behind the Superman: The Animated Series episode, World's Finest, which brought Batman and the Joker into the picture. Both Superman and Lex Luthor see both the Joker and Batman as non-superpowered beings not worth their time and energy. By the end, Batman has scared the crap out of Luthor(something even Superman never even managed) by breaking into his penthouse, and the Joker comes closer to killing Superman than just about any other villain had previously, almost kills Luthor, takes over the mob, and levels a good portion of Metropolis to the ground.
 * At the beginning of Avatar: The Last Airbender, Commander Zhao regards Prince Zuko as a weak, bratty teenage punk. They get into an argument, and Zuko challenges him to a duel, which Zhao fully expects to win. Not only does Zuko soundly beat him, but he spares his life as well.
 * And Zhao does it again against Aang in a later episode; when warned by his former master that he is not ready to fight the Avatar, Zhao arrogantly replies "I think I can handle a child". The result ? Aang makes him look like a fool by tricking him into destroying his own fleet, thus defeating him without any shot. Obviously, Zhao never learns.
 * On the surface, Zuko's Uncle Iroh looks like a quirky old man who'd rather do little else besides sleep and drink tea. Of course, he's exactly that, but he's also the Dragon of the West and will kick your ass six ways from Sunday if you give him a reason to. There's more than a few of his foes that don't seem to get that.
 * When Captain America (comics) escaped imprisonment inside the Skrulls' ship in The Avengers: Earth's Mightiest Heroes, the Skrull commander immediatly assume there is no need to bother because "This man isn't a treath. There is nothing special about him". A few minutes later, Cap has freed all prisonners onboard, convinced them (some of them being villains) to team up and led them to a ship which they use to escape. The Super-Skrull even lampshades his commander's stupidity and tries to kill Captain America for, declaring him too dangerous to be left alive.

Real Life
""We only have to kick in the front door and the whole rotten structure will collapse.""
 * Once, a Spartan envoy came to Cyrus protesting the fact that his conquests were getting closer to them than they liked. Cyrus asked an aide, "Who are the Spartans?"
 * To be fair, he probably legitimately didn't know -- the Spartans were blithely assuming that tales of their exploits were known worldwide, while Cyrus ruled a vast empire that was only just moving into the region. Cyrus was too smart to intentionally snub a diplomat -- nevertheless, the Spartans took it as a massive insult. A few years later, he got his answer. His successor Xerxes got a much more comprehensive education three generations later.
 * The Athenians had something of an inversion during the reign of Darius: When the Ionian city of Miletos rebelled and set up a democracy, Athens set 1,000 hoplites to support the Milesians against the Persians. The Athenian brigade was so successful, they managed not only to (temporarily) rescue Miletos, they also marched up to Sardis, the capital of the Persian satrapy (province) of Lydia, and torched it. Upon receiving word of the attack, Darius (after having a fit) asked, "Who are the Athenians?" Presumably after getting an answer, he is said to have shot an arrow into the sky and said, "God grant that I may punish the Athenians." According to Herodotus at any rate, this led to the ill-fated Persian expedition at Marathon and eventually the Persian invasion of Greece under Xerxes (during which he did in fact punish the Athenians--by burning it down--but ended up wondering whether it was worth the trouble).
 * World War II. The USSR decided to conquer Finland. Tiny country, no big deal. No need to, say, plan for the campaign stretching into winter and give your troops proper winter gear. Or to give them uniforms that don't stand out so completely against the pure white snow. After all, it's not like the Finns are going to suit up in nice warm uniforms that are also totally white and then ski around the country turning your troops into target practice... right?
 * And USSR, at least in Hitler's eyes. Partially because of its somewhat poor performance with Finland.


 * Rather ironically making some of the same mistakes Russia did when invading Finland.
 * What people forget when bringing this up, however, is that the so-called "poor performance" didn't matter. Both instances the USSR took on Finland, the Soviets won no matter how badly the Finns bled them. Finland ended up ceding territory to the USSR each time. Territory they still hold to this day. It wasn't even a Pyrrhic Victory by Soviet standards since even the massive disparity of losses was, ultimately, tiny given the massive reserves the USSR brought to bear. So in a recursive case of this trope, modern internet audiences go "LOL, Russia lost against Finland," ironically underestimating the larger power.
 * When Maria Theresa's father died and she took the throne, the princes of Europe thought she was no more then a Damsel in Distress. What they found was that she was a Lady of War.
 * Rudyard Kipling (somewhere or other) told this story about how western sailors in Japanese ports would have a wild Bar Brawl. And then some nice polite little cops would walk in. The sailors would turn at them and laugh. Only to find that these cops were all former Samurai...
 * The Jews in the the Jewish Revolts were a tiny province that gave Rome the hardest fight she had had for ages. So hard that just subjugating them was considered worthy of a triumph and made the commander The Emperor.
 * In the 12th century, the Khwarezmian emperor who ruled much of Greater Iran, thinking that Genghis Khan was only the leader of a small, weak group of nomads, killed and shaved his messengers to humiliate him. The Mongols responded by completely demolishing his empire and adding it to their own in a campaign that was brutal even by their own standards.
 * And we're talking about an army that considered dragging your enemies to death from horseback a legitimate combat tactic. Not even just your enemies, but their peasants as well.
 * In November 2010, two drunken yobs thought that it would be a good idea to start a fight with three men they met in the street. Unfortunately for the two, the three people that they picked a fight with were George Cross winners Peter Norton of the British Army and Matt Croucher of the Royal Marines plus Victoria Cross winner Mark Donaldson of the Australian Special Air Service Regiment. It didn't end well for the both of them. Read about it here: http://www.thesun.co.uk/sol/homepage/news/campaigns/our_boys/3227540/Military-heroes-in-yobs-rout.html
 * It's actually a rather common occurence for thieves to horribly underestimate the people they rob. On any given occassion, that random passerby they attempt to hold up might just be a Badass Normal or packing heat...
 * Yeah http://www.dailymail.co.uk/news/article-1218651/Thugs-attack-men-dresses--turn-cage-fighters.html
 * A local news item in Tampa during the 1980s involved some men who attempted to mug an attractive, harmless-looking lady in a mall parking lot. She happened to be a third-degree black belt, and a former AAU national champion in Tae Kwon Do. It was a long time before those guys were in a condition to try to mug anyone else.
 * Speaking of thieves, once upon a time there was a Malaysian snatch thief on a motorcycle who rode up and tried to snatch the chain of this old grandma walking along the road. Grandma kicks him off his motorcycle, picks up a sharp object on the road, and beats him until he begs for mercy. After that, she ties him up, gags him, and calls the police, who promptly rush him to the hospital.
 * Most hilariously, while the article translates "Mu tak molek" as "You're disgusting", it actually means something a little more along the lines of "You are not cute!"
 * Chuck Norris was taking a walk one day when two men came up to him and told him to give them his wallet. Police were called and came by later to find Chuck Norris standing idly while both men sat along the curb with broken arms. The cop laughed and asked, "Didn't you guys know who he was?" The two men replied, "Yeah, but we thought all that T.V. stuff was fake."
 * Well, he does have a black belt in Brazilian jiu-jitsu, a martial art that has arm-breaking techniques as some of the fundamental moves that beginners first learn...
 * This happens in many cases with Israel. Its Arab neighbors believed they could simply take over Israel with Zerg Rush and tank spam, but they ended up getting soundly defeated practically three times in a row.
 * One common thread for the 20th century was the way authoritarian regimes constantly underestimated the will of democracies to fight (and win) when they were forced into it.
 * Standing armies often underestimate the dangers of desperate and angry civilians.
 * There's a Japanese story, possibly apocryphal, about two Samurai who walked into a tea house and sat down to drink. At the other end of the tea house, they saw a filthy, disheveled man eating rice with chopsticks. They both pointed and laughed at the man, saying he smelled so bad that flies were buzzing around his head. Without looking at the samurai, the man calmly crushed each fly in the air with his chopsticks. The two samurai, realizing they had just insulted the legendary swordsman Musashi, quickly left.
 * Many a kid has picked a fight with another kid on the school wrestling team thinking that wrestling is just a bunch of flopping around and completely useless for anything other than wrestling matches - and gotten their asses handed to them in humiliating fashion. However the popularity of MMA and the success of wrestlers in it has made this far less likely to happen.
 * Casey Heynes vs Bully. Casey gives him one hit, then blocks him a few more times. Then picks him up and throws him to the ground, promptly becoming a viral sensation.
 * Napoleon called the British a "nation of shopkeepers." That nation of shopkeepers fought him for ten years, blockaded his empire, starved his people and exiled him to a tiny island in the middle of the Atlantic Ocean.