Bob knows that Alice is stupid: She's a woman, and women are stupid - never mind that Alice has a PhD and an IQ of 150, she's still a woman... and women are stupid, thus Alice is stupid. If Bob finally accepts that Alice is indeed smart, he might resort to claiming that she is not really a woman. Bonus points if Bob uses Alice not being stupid as an example of the principle that women are stupid either because she's too smart to be a real woman, or as "the exception that verifies the rule". Also bonus points if "Alice" isn't even a woman, and Bob simply assumed a neutral Internet nickname to be female because he thinks the person is stupid. Alternatively, Alice actually does something stupid one single time and Bob draws the conclusion that she is (and all other women are) always stupid.
Of course, this is all simply Bob doing some really bad categorism: Racism if it's about race, sexism if it's about gender, ageism if it's about age, homophobia if it's about homosexuals, and so on. If Alice listens too much to him, she may come to suffer from Internalized Categorism.
This trope can come into play in two ways: Either establishing or upholding. The first is often in the form of making a raging overgeneralization about a group - one that cannot possibly be true in all cases, and is often so outrageous that it might even be hard to find a valid example. The second is upholding the prejudice in the face of overwhelming evidence to the contrary, often with the help of Confirmation Bias, Theory Tunnel Vision, Insane Troll Logic, and/or I Reject Your Reality.
Sometimes combined with Straw Affiliation to make it extra insane: If you have Trait X you belong to group Y, and everyone in group Y are Z. For example, if you are a man who has long hair, you obviously turn over gravestones and nail live kittens to church doors. Because men with long hair are satanists, and satanists do that kind of stuff. Compare Nonsense Classification and Insane Troll Logic. When used by characters rather than the narrative itself, tropes such as Depraved Homosexual, Bondage Is Bad, and All Gays Are Pedophiles are often played as aggressive categorism. With the first two tropes, this come in the form of reducing people to their sexuality and reducing the sexuality to the sex. With the last two tropes, it comes in the form of deciding that everyone who have a certain quality X also has the unrelated quality Ynote . This line of thinking easily leads to an Abomination Accusation Attack. When the aggressive categorism grows into being mentally unhealthy, it often takes the form of a phobia or a tendency to see everything in black and white.
Often done by the Racist Grandma, the He-Man Woman Hater, the female character who Does Not Like Men, the Straw Feminist, the Windmill Crusader, the Straw Loser, or the Noble Bigot, and is often used to highlight how shallow the character's thinking is. This is often Played for Laughs at the character's expense or as a joke in its own right. Rarely done by more nuanced and Played for Drama characters, such as the Troubled Sympathetic Bigot. May lead to Irrational Hatred. Note that "There Are Two Kinds of People in the World" is usually not this: Even when it's not a joke or metaphor, it's usually restricted to one parameter. In a school scenario, this leads to an Absurdly Divided School.
Compare Double Standard.
- Cross Ange: In a world where mages are commoners, every muggle is treated worse than a witch; not only are muggles forced to a deserted island where they secretly fight an invasion force of alien dragons in highly unstable cool mecha with a disturbingly high death rate, but the friends and family who actually cared for them slowly erode in opinion until it's as if they hated their muggle companion all along. Including Ange's beloved little sister Sylvia. (In her possible defense it might have been her older brother Julio convincing her Ange was to blame for the death of their parents.) Muggles are treated like devil spawn even if their behavior doesn't change or they show exceptional merit and mercy. Though this is only partly their fault: it's revealed near the end that the mana they use is like meth, only it makes them obedient to an abusive thousand-year-old pervert. In response to this, said muggles have no qualms with opening fire on civilians for their past torments (said civilians usually shown having guns, and planning to use them first), but show mercy to traitors in their ranks for harsher war crimes.
- One major exception: Momoka is a mage who never loses her loyalty to Ange, even though she thinks that most muggles are scary dangerous. This is explained by her abnormally high willpower, which allows her to use magic on the pervert who invented mana and controls it like a computer.
- Growing up as an orphan, Fuka from ViVid Strike! has developed a strong distaste for rich people. While this generally applies to anyone who looks down on her because of her poor background, she specifically dislikes rich people for being the ones to change Rinne's personality after they adopted her. She slowly starts to get better through interacting with Team Nakajima, but she was still hostile at first after realizing they went to a "rich girls' school."
Fuka: I don't think you rich girls understand how us commoners struggle to live each day.
- Many of the boys in Innocents Shounen Juujigun display this when it comes to the "infidels" (aka anyone who isn't the exact right kind of Catholic), assuming that anyone who doesn't share their religion is going to be a literal demon. Many of them even express shock that people from other religions don't have horns and other animal features. Nicolas and Michael are the worst offenders.
- In Chick Tracts, protagonists are likely to do this to Christians or non-Christians depending on whether they are Saved or not. Those who do it to Christians are always proven wrong (and either get Saved or go to hell), while the Christians who do the same thing always turn out to be right.
- In Bitchy Bitch, Midge's insufferable fundamentalist coworker does this all the time. For example, she "knows" that the recently hired temp is a witch who can put curses on people, because she has a necklace with a pentagram.
- Bitchy Butch does this all the time, living in her own unhealthy little world where all men (and all heterosexual women) are total Jerkasses. The only time she managed to see a guy for the nice person he really is, she refused to see that he's male.
- In the 4th album of Whatever Love Means, The rant about Jihad Jane plays this trope on two levels. First, Liv accuses mainstream society of doing this to Arabs and Muslims, assuming that they are all terrorists. Second, she focuses on the fact that Jihad Jane was blond, female, middle aged and dressed in a certain style common among western women. Having established that, she moves on to portray a scenario where all western women with this style are treated as if they were terrorists.
- In one Samir strip, one white woman try to get the protagonist (a brown man) arrested for trying to rape her. He didn't come closer than 20 yards, much less touch her. But he did walk on the same street as her. This comes as the comedic punchline after a long angry Internal Monologue of his, complaining about prejudice against men and against non-whites. The woman is portrayed as being totally honest in her analysis of the situation.
- MAD used to run a recurring feature called You can't win with a bigot which alternated examples of bigots contradicting themselves in ways that ensured their interpretation of events always conformed to their prejudices.
- The Ultimates: Superheroes, marines, are all the same imperialist crap for Thor.
- In Son of the Desert, Havoc, Breda and Fuery believe that all Ishvalans are fanatically religious. Edward tries to call them out on generalizing an entire group before snapping and outting himself as Ishvalan.
- From Savior of Demons:
Goku: "It's simple, Frieza. I don't like to see anyone, regardless of who they are, getting hurt. Not even someone like you. If you can't fight back, well, fighting's no fun." He shrugged.Frieza: "Th-that's impossible!" Frieza spluttered, "You're a Saiyan, and as such you are bloodthirsty by nature!"
- This is actually true, but Goku hit his head on a rock as as small child, altering his personality just enough to lose the bloodthirstiness but keeping the love of fighting.
- In Tucker & Dale Vs. Evil, Chad gets all of his friends to believe that the local hillbillies are trying to murder them. He hates hillbillies because a hillbilly murdered his parents. Eventually he discovers that his father was the hillbilly after all. Not all of them are evil psychos, but this one was and it seems to have been passed on to Chad.
- In Show Me Love, Markus is the obvious case, with his inane rant about how women can't possibly understand cellphones and men can't possibly understand makeup. However, it's implied that the people in general are just as narrow-minded, they just don't flaunt it like he does. Life in a small town is hell.
- In 12 Angry Men, Juror #10 is one of the last holdouts for a guilty verdict. As time goes on it becomes clearer and clearer that he doesn't care about the evidence; the kid is guilty because "there's not a one of them that's any good" (referring to the Latino defendant). The 1997 version is far more explicit in this regard: Juror 10 delivers an angry rant about how "those spics stay high on dope and fight all the time" and "these wetbacks are multiplying like rabbits." He's not at all concerned about guilt or innocence, he's just wants to "get him before his kind gets us."
- The Man Who Killed Don Quixote: Javier is under the delusion that he is Don Quixote and film director Toby is Sancho Panza. When Toby wants to read something, Javier refuses because, as a peasant, Toby is illiterate.
- At the beginning of Disenchanted: The Trials of Cinderella, Ella Coach's most closely kept mindset is "Working class = Good" and "Aristocracy and Upper Class = Evil," because of her Freudian Excuse: Her beloved mother worked in a sweatshop, and died of illness because she was couldn't afford time off. After Ella's father's inventions make him rich and he remarries his business partner, she holds his new wealth and status against him and attempts running away.
- Smallville: Jonathan Kent is firmly convinced that all Kryptonians are evil by nature. When Martha points out that their son is a Kryptonian himself, Jonathan simply replies that Clark is the exception because he was Raised by Humans and with human values. To be fair to Mr. Kent, most if not all of the Kryptonians that appear in the series are high-and-mighty assholes at best.
- Street Justice: The race-prejudice variant forms part of the plot of "Black or Blue," where Willis is suspected of shooting a white pizzeria-owner simply because he's a black man who happened to be in a predominantly white part of town at the absolute wrong time.
- Parodied in Nanne Gronvall's song Fördomar. The protagonist spends the song doing aggressive categorism against all kinds of people while considering herself to be enlightened and free from prejudice.
- Defied in Prozzak's Be As, which is about not letting people lock you into narrow categories such as white/black or straight/gay.
- In Arne Anka, the protagonist makes a jerky attempt to flirt with a woman, who responds by exclaiming to her friend that all men are the same kind of pigs. This causes Arne to go on a rant about starting concentration camps for men, and giving the woman the "Sieg Heil" salute.
- In Crysis: Legion, Colonel Barclay refers to The War of the Worlds when discussing the Ceph. Gould is Mind Screwed by this - he's a Properly Paranoid Conspiracy Theorist who has feared The Government and especially the military his entire life, and "lifers who read ancient science fiction dont fit comfortably into his worldview."
- The Angels in the Disgaea series hinge in and out of this. Angels generally believe that Demons are pure evil solely because they're demons. As Angels see themselves as harbingers of complete good, they lump every Demon into the category of "evil" just because. Recent games imply that they're slowly starting to change.
- In Disgaea 5, it's mentioned that Demons seem to suffer from a little bit of this toward Angels; explaining why Christo hid his identity the way he did. To be fair, they have been the ire of every known Angel for who-knows-how-long. (Heck, it's even a voice option for the Male Angel class!) If the possibility of this being a prequel is true, however....
- Happens several times with the Qunari in Dragon Age due to their extremely rigid society.
- If a female Warden recruits Sten in Dragon Age: Origins, a conversation will eventually ensue where he states that he doesn't believe you're a woman, because Qunari women cannot be warriors. Despite the deep cultural divide, you can eventually make him respect the Warden as a warrior. In Dragon Age: Inquisition The Iron Bull states that even though he's lived among non-Qunari long enough that the culture shock is less severe than Sten's he still mentally categorizes female fighters like Cassandra as men in his mind. He also states that Qunari women can in fact be warriors if the show particular talent in that area — they just get treated like men for all intents and purposes. This also means that they're very accepting of transgender people, because as they see it if someone's living life as a particular gender then they are that gender, biology be damned. They also have a deceptively precise definition of "warrior" tied into their caste system; several roles that can be of any gender also serve as active combatants, but since it isn't their main job they aren't technically considered warriors.
- In general mages are looked down upon even more than in the rest of Thedas, being treated essentially as animals that need to be leashed like mad dogs. If a Mage Hawke in Dragon Age II manages to win their respect then clearly he/she isn't a mage, he/she is just a perfectly ordinary person who happens to have innate magical powers.
- Played straight with Lampshade in The Simpsons. See page quote.
- Shows up in regards to "Those lousy teens" as well. When Homer and his drinking buddies get wasted and cause a lot of damage with his car (with a blatantly visible trail leading to his car parked on the front lawn), the police conclude that it was the work of "punk kids", and enstate a curfew.
- Cartman from South Park does this with just about any kind of minority, often in utterly bizarre ways ("gingers have no souls," for example). However, sometimes he's portrayed as actually being right about some things, to the perpetrators' own annoyance (e.g. Token's ability to play bass, and Kyle carrying "Jew-Gold" around his neck).
- Peridot in Steven Universe initially displays a reductionist attitude towards the Crystal Gems en masse. Garnet is a freak and a "filthy war machine" because she's a permafusion, Pearl is a brainless ornament who can't compete on Peridot's level in terms of technical skill (even though we've seen Pearl build a fully functioning battle robot in about thirty seconds, and a working space ship in a couple of days), and she "jokingly" calls Steven an "abomination" to his face because he's a human-Gem hybrid. Amethyst gets the benefit of being "the only real Gem" in the Crystal Gems, who gets tagged as "defective" by Peridot because of her size but still, by Peridot's lights, should be the Crystal Gems' leader... because she's a Quartz Gem.
- In Futurama, Leela's old martial arts instructor told her that she'd never be a good fighter because, as a woman, she lacks "the will of the warrior". Many years (and badass levels) later she encounters him again and challenges him to a fight; he says it's a foregone conclusion that she'll lose, thus he's already won without needing to actually fight her. She finally gets the chance to curb-stomp him at the episode's climax.