You Dirty Rat

"Rats is rats, past, present, and forever. Weasels change, but rats is rats!"

—John Wesley Weasel, The Book of the Dun Cow

In fiction, mice are often portrayed as sympathetic characters. They are always cute, nice, and sometimes even sweet, but often they are also portrayed as honest, brave, and forthright. Rats on the other hand - possibly because of certain historical events - are Exclusively Evil. Also, a mouse is apparently helpless while a rat can bite back hard (and sometimes does discourage a cat who is too pampered and not a real hunter). Consequently, if a cat is chasing a mouse, the cat is almost always the villain; if the cat is chasing a rat, he's almost always the hero.

Could be seen as a type of Fantastic Racism. See also Nice Mice. Compare with Cats Are Mean, Reptiles Are Abhorrent. Subtrope of What Measure Is a Non-Cute?.

Trope Namer is a quote wrongly attributed to James Cagney. The actual quote, for those who are wondering, is "That dirty double-crossing rat!"

Examples of You Dirty Rat include:

Anime and Manga

In Gregory Horror Show, Gregory and his family either want to trap the protagonist's soul forever (Gregory), eat it (his mother), or torment it (his grandson). All three of them are rats.
In Heat Guy J, Ian has been sent to do some recon for Clair. However, Ian gets caught by the very man he's investigating, Senator Noriega. Noriega says, "Well, look what I've found: a dirty little rat." Ian takes off his night-vision goggles and replies, "Am I really the one who's the rat?" before being shot in the head.

Comic Books

In 1930s Mickey Mouse Comic Universe comics, Minnie's cousin Ruffhouse Rat isn't evil—but he's a lazy, egotistical flop of an athlete who essentially makes Mickey and Minnie solve his problems for him.
A very strong aversion: Master Splinter in any incarnation is a wise, gentle, and patient fellow. Just don't threaten his adoptive sons.
- The Rat King from the cartoons plays it more straight though.
In Blacksad the bar patron who helps Blacksad track down Leon Kronski and tries to kill him, turning out to be working for Statoc is a rat. Lampshaded by Blacksad in his internal monologue.
Averted in The Tale of One Bad Rat, a miniseries about a teenager who runs away from home after being sexually abused by her father; her only companion is her pet rat, and she can get quite indignant when people say that rats are dirty or creepy.

Film

Disney Animated Canon:
- As far as Disney films go, Lady and the Tramp features a rat that threatens the Darlings' baby but is stopped by The Tramp, and Cinderella features heroic mice who help the title character deal with her stepmother and stepsisters.
- In The Great Mouse Detective heroic detective Basil of Baker Street is a mouse, while his arch-nemesis, Professor Padraic Ratigan, is a rat, of course (though he hates being called that). The book reverses this, having the professor as a mouse.
Averted in Ratatouille, where the main character is an intelligent, urbane rat with a gourmand's taste in food and the ability to cook like a classically trained chef. Of course, most of the other rats are classless, tactless layabouts, but at least they aren't evil.
- In the Spin-Off short, "Your Friend the Rat", Remy and Emile try to argue for the reconciliation of humans and rats, using historical facts presented to various styles of animation. Among other things, they explain that The Plague was actually caused by fleas that got attached to black rats, not by the rats themselves, and in fact, the brown rat had supposedly helped to end the Plague.
- Also subverted in Ratatoing, a cheap knock-off of Ratatouille. Rats are both heros and villains, being a Mockbuster.
The same goes in The Secret of NIMH. Except for Magnificent Bastard Jenner and Brutus (who, to be fair, is only doing his job), all the rats are benevolent. In particular, Justin is a hero who is designed to be as dashingly handsome as one can make a rat and still be recognizable as such. It should be noted that had Brutus wanted, he could have very easily killed Mrs. Brisby with that spear. Instead, he repeatedly intimidated her by swinging it in her direction, and didn't pursue her when she ran off.
Again again in Flushed Away, where the rats are, as a group, no more good or evil than any other random population.
Averted in The Brave Little Toaster Goes to Mars and The Brave Little Toaster To The Rescue with Ratso.
Yet another aversion occurs in The Wind in the Willows with Ratty. Sure he's actually a Water Vole, but voles are close enough to rats for government work.
In Enchanted, the rats do a considerable share of the housework while under the influence of Giselle's "Happy Working Song". Only one mouse is seen to help out, and it's only there because a rat wouldn't fit in the bathtub drainhole.
In one adaptation of The Country Mouse and City Mouse, the bad guy was a rat.
The Mice in An American Tail are all virtuous, loving immigrants. Warren T. Rat, on the other hand, isn't even a rat, but a cat, and one of the bad ones at that.
Chicken Run features rats who peddles junk to the hens in exchange for eggs. They're enterprising, but not evil.
In Coraline, she's shocked that the cat would kill a mouse like that. Little did she know...
In Cat City, the rats are villains (although of the ineffectual sympathetic kind).
In The Princess Bride, Wesley gets attacked by a giant rat in the forest. He manages to kill it after a few minutes.
- Although it actually looks a lot more like a giant opossum than a rat.
In Willard, the title character has a pack of killer-attack rats who remove anyone who gets in Willard's way.
- This is subverted in the sequel, Ben, wherein the pack of rats defend a small boy from bullies.
In Nosferatu, the vampire looks quite rat-like, keeps loads of them in his coffins, and spreads the plague.
Averted in Teenage Mutant Ninja Turtles with Splinter. But then again, there's a villain known as The Rat King who hypnotizes the rats of New York into doing his bidding.
In Indiana Jones and the Last Crusade, swarms of them fill Venice's catacombs. It's known that Henry Jones Sr. fears them, just like his son fears snakes.
Averted in Home Alone 3, in which the kid's pet white rat, Doris, is depicted as a cute friendly companion.
This trope is the reason the Mouse King from The Nutcracker was changed to the Rat King in The Nutcracker: the Untold Story.

Literature

Used horrifically in Nineteen Eighty-Four.
The Underland Chronicles plays this straight at first, then subverts it big-time.
In Harry Potter, Ron Weasley's pet rat Scabbers turns out to actually be the animagus Peter Pettigrew in disguise. Pettigrew, of course, was the traitor who sold Harry's parents to Lord Voldemort. He's even described as rat-like when he's in human form.
- This takes inspiration from Rowling's sister's phobia. Rowling herself doesn't mind rats. There is also a chapter that has magical rats showing off in a store, playing jump rope with their tails, so not every rat is portrayed as villainous.
In The Tale of Despereaux, the mice are all good (cowardly, but good), while the rats are all evil. Chiaroscuro the Rat, an innocent born into a corrupt society, has to deal with his species' stereotype.
- Though they seem to get along with humans during the opening and ending.
The rats in Redwall are always criminals. They're even referred to as vermin.
- Well, except Blaggut, but he's dumb as a stump. (And friggin' adorable.)
- By Loamhedge they seem to have taken back the word "vermin" for their own, as they actually refer to themselves as vermin and seem proud of it.
Played straight in The Book of the Dun Cow with Ebenezer Rat, an egg-eating and violent rat, although it should be noted that he is nowhere near the most evil character in the book and dies in battle with one of the real villains.
Played with in Garry Kilworth's Welkin Weasels series. The black rats are Exclusively Evil, while the Norway rats are lovable fops.
- This sounds fairly close to their behavior in Real Life.
- Similarly in his novel House Of Tribes: the rat, Kellogg, is evil and a murderer.
Templeton Rat from Charlotte's Web isn't actively evil, but he's certainly selfish, arrogant, and greedy. He has to be bribed into helping Wilbur the Pig.
David the rat nothlit in Animorphs, although he was forced into rat morph to keep him from threatening the rest of the group. He does return just as evil in a later book, though.
Watership Down uses this one. Hazel finds and saves a field mouse from a hawk. In return, the mouse tells him where there's a stretch of really good grazing for the rabbits. The rabbits are later attacked by a pack of rats just after escaping from Strawberry's original warren. Then again, later in the book Hazel, during the first trip to Nuthanger Farm, stops to ask a rat for directions and gets a quite civil answer, even if, as the narrative notes, the rat had no particular reason to be friendly.
- Possibly the hostile ones were defending their home, as the rabbits had bedded down in an abandoned barn suitable for rats to live in. The rat at Nuthanger farm was simply walking by.
Discworld:
- Examined on both sides in the so-called "young adult" novel The Amazing Maurice and his Educated Rodents. Contains children's-book rats in waistcoats, rats who spoil human food supplies with urine, rats who tap-dance, rats who kill other rats and devour their corpses, telepathic rats, rats who make deals with cats, and rats who manipulate humanity's fear of rats to their advantage. Now guess which rats are the good rats.
  - The correct answer being: all of them except the telepathic rats.
- Much earlier, Pratchett subverted the "cute friendly mouse" side of this trope with Definitely Not Squeak, a mouse who began talking under the influence of Moving Pictures. He was outraged when told that mice are considered cute and sweet by humans, as he'd been the toughest mouse Badass in the house and proud of it.
- In Reaper Man, Death acquires a sidekick, the Death of Rats, whose form sort of implies rats are similar to humans, as they conceptualize Death by anthropomorphizing it, rather than by picturing something that causes their deaths (i.e. the mayflies see Death as a trout.) Perhaps not Rats Are Good, but definitely Rats Are Smart, or Rats Are Like Us.
Mostly averted in Mrs. Frisby and the Rats of NIMH, and its sequels and adaptations. Indeed, its author received a number of letters asking just why he had rats as sympathetic heroes in his book.
Subverted in The Roly-Poly Pudding, where it's unclear whether the rats actually intend to harm Tom Kitten or are just trying to scare him. (Conversely, there's no question that the cats have eaten rats in the past, and continue to eat them in the future.) This relatively even-handed treatment probably occurs because Beatrix Potter kept a pet rat when she was a girl.
The mouse part is subverted in The Hitchhiker's Guide to the Galaxy. Mice are actually the smartest animals on the planet Earth, which itself was a sort of massive, living distributed computing experiment to determine the Ultimate Question. When Earth is destroyed, they decide that they need to get what data they can salvage by cutting it right out of Arthur Dent's brain.
Avram Davidson's short story "The Tail-Tied Kings" deals with a rat warren threatened with destruction by their "slaves" (the humans they steal food from) and the escape of the aforementioned Kings (and Queens). This troper was surprised to discover mention of such Kings in the Mythology section.
Bubo, a rat hero of A Night in the Lonesome October is introduced as a Familiar with a knack for shady deals and corresponding manners. He turns out to be much more sneaky, but in general a pretty decent critter.
Rats are quite some pests on Warrior Cats, but the most evil is seen on Firestar's Quest, where a rat speaks cat language and hints that his kind drove out the former SkyClan. And then, there were the rats that caused almost all of ShadowClan to get sick in Rising Storm...
Mary Gentle's Rats—who are generally the dominant sapient species of any work in which they appear—tend to be crooked, manipulative, ambitious, self-centered, and bigoted—in other words, about as bad as Humans Are the Real Monsters. (And they're ruled by rat kings with their tails deliberately knotted together.)
Averted in Spider Robinson's Telempath. Rats are very dangerous — the main character lost his left arm after rat bites got infected — and at one point near the book's end he confronts hundreds of them. "Some were the size of tomcats. They were like a great grey carpet of death." He manages to empathically suggest a truce. The rats don't attack. One of his friends wonders, "Can even that war be ended someday?"

Live-Action TV

Played with in Yes Minister, when protesters keep Sir Humphrey from clearing a particular copse of trees because it was home to a family of badgers. He convinces them that there are no badgers in the woods, only rats, and the protesters leave.
Averted with Rizzo the Rat of The Muppets, and his rat friends, who are genuinely friendly (except when you say the wrong things). Although they are still greedy and gluttonous.
Nature shows about snakes and similar predators tend to show them killing or swallowing rats, even if they aren't a major part of the predator's natural diet. This is because rats don't garner much sympathy from viewers: if a snake eats a bird, frog, or rabbit, it seems like more of a Downer Ending than if a rat becomes lunch.
Seen in Fawlty Towers where Manuel's pet 'Siberian Hamster' becomes a pest that must be got rid of before the health inspector arrives.
For some reason Frasier and Niles Crane are both squicked badly by Daphne's description of the show rats she used to raise. All they can think of is the rats of the Black Plague, despite the fact they are both mental health professionals who should be familiar with the use of rats in psychological and medical studies. In another episode it's revealed they themselves were named for their mother's lab rats.

Newspaper Comics

In Pearls Before Swine, Rat is a total Jerkass and Small Name, Big Ego that is often out to get a quick buck. However, he is also often a Jerkass Woobie.
Dilbert subverts this to hell and back with Ratbert, who is actually extremely friendly and cheerful.
Inverted in Krazy Kat with Ignatz Mouse.

Oral Tradition, folklore, Myth and Legend

The mythology surrounding the phenomenon of the rat king (a group of rats whose tails are knotted and matted together with filth) tends to give them certain supernatural and generally unpleasant powers. Though it did (rarely) happen in real life, increased hygiene means that rat kings are probably not likely to occur ever again.

Radio

"Three Skeleton Key", a 1950 episode of Escape narrated by Vincent Price, involves a trio of Lighthouse Point keepers who find themselves besieged after a derelict ship crashes onto the nearby rocks and ejects its "passengers": an army of ravenously hungry rats.

Tabletop Games

Most rodent creatures in Magic: The Gathering are Green (the color of life) except for rats. All rats are Black (the color of death).
- However, Dark Is Not Evil, and while many rats are in fact pests, some of the Kamigawa block Nezumi are decent, if anti-heroic.
In Warhammer Fantasy Battle, the Skaven are Exclusively Evil rat-men who practice foul sorcery and use chaos-empowered steampunk technology to wage war on everyone else (even the other Exclusively Evil races).
In earlier editions of Dungeons & Dragons, wererats were Always Lawful Evil (along with the Chaotic Evil werewolves), while most other forms of lycanthrope were good or neutral. With Fourth Edition, this has been changed so all lycanthropes are Exclusively Evil.
- And then there's Planescape's Cranium Rats—one isn't smarter than a normal rodent, but their telepatic abilities bind their little powers and intellects into Hive Mind, so the pack of three dozens can cast minor spells, half-hundred is as smart as an average human, and so on. They're Neutral Evil, and some or all of them are spies of illithid god Ilsensine.
Subverted by the Nezumi (aka "ratlings") in Legend of the Five Rings; they're primitive and rather crude, but basically good guys.
- When Five Rings was converted to Dungeons & Dragons for the 3rd Edition Oriental Adventures book, nezumi were portrayed as Chaotic Neutral. However, the book noted that ratlings were often evil in other settings.
The Ferrans of Talislanta tend to be nasty, thieving little scavengers. They have no concept of hygiene and can spray like skunks. However, the Ferran in the Talislanta tie-in anthology manages to be something of a Woobie.
The Beshilu of Werewolf: The Forsaken are Hosts, spirit parasites that possess humans, hollow them out body and soul, and ride around the resulting meat puppet. They're singularly obsessed with gnawing open holes in the Gauntlet, leaving gaps to the Shadow that allow pretty much anything to slip through unfettered. The werewolves don't like this.
- The predecessor game, Werewolf: The Apocalypse, had the Ratkin, one of the many Changing Breeds. They decided the werewolves weren't going far enough in their quest to save Gaia from the deprivations of the Wyrm, so they basically became chaos-mongering terrorists and saboteurs.

Theatre

The Mouse King in the Nutcracker Ballet is probably one of the more famous examples and a subversion of the "mice are nice" part. He even has three heads in some versions of the story.
- See "rat king" under mythology. Now, imagine that in place of one guy in a costume with three heads. No wonder all the other characters are terrified of him.

Video Games

The Qiqirn in Final Fantasy XI are a race of beastmen rats who are on not-really-hostile-at-all terms with The Empire of Aht Urhgan. That is, they like the "clink-clink" people carry, and will do anything to get it. Essentially the Near-Eastern version of Goblins, just more peaceful.
- The Burmecians of Final Fantasy IX are anthropomorphic rodents. The word 'Rat' appears to be a derogatory term for them, but they are mostly on the side of good.
Apparently most of the Rattkin in Wizardry are thieves (there's also a Rattkin scientist), and their high-ups are The Mafia, but in general they are not worse than any other faction present and better than some, and no more or less prone to generate an aggressive Random Encounter. That's just their ways. In Wizardry 8 some work with the party against Big Bad—it turns out that NPC followed him to another planet to avenge for crossing them on Guardia back in VII.
Rattata and Raticate in the 1st generation of Pokémon. They aren't really evil, but are often used by Team Rocket grunts and are Com Mons, so most players generally get tired of seeing them. Also, are contrasted by the Nice Mice Pikachu and Raichu.
- In Pokémon Sun and Moon, we're introduced to the Alola Region's version of the Rattata line. They're trouble-making Dark/Normal types that look and act the part of a gang of criminals: the mustached Alolan Rattata will steal food from people at night and give it to the Alolan Raticate in charge of their pack, where they proceed to hoard it all like the Fat Bastards they are.
The rats in Little King's Story appear quite mischievous, and the narrator seems none to fond of them. In the end, it's very justified.
Don't forget the army of anthropomorphic rats in Battletoads. These sleazy space pirates fit this trope perfectly. And you'll come to hate rats after Sc uzz.
Jimmy Two-Teeth in the Sam and Max games, a small-time ruffian rat who is also the Butt Monkey. He is apparently sent on a bus in Season 3 -- but not before (it is suggested) causing an outbreak of bubonic plague at Max's bidding.
- Rats reappear in Season 4, petty criminals at worst but generally good-natured. None of them are nearly as violent and dangerous as Max.
In Majesty Ratmen are a milder version of Warhammer's Skaven; they're like goblins, except their habitats are broken sewer pipes, which means they can pop up randomly in the middle of your town rather than some distance away.
Speaking of Warhammer, The End Times: Vermintide is basically Left 4 Dead, but with you slaughtering hoards of ratlike Skaven instead of zombies.
Played straight in King's Quest I. The guard rat will kill Graham if he gets too close. He is amicable to bribery, though.
Rat demons are the lowest creatures in the demon hierarchy in Jade Empire.
Rats are the weakest enemies in Legend of Kay.
Rats are almost always evil disease-carrying pests in The Elder Scrolls series. One notable exception is the initial Fighter's Guild quest in The Elder Scrolls IV: Oblivion. You have to save a woman's beloved pet rats from hungry mountain lions. In Skyrim they are replaced by Skeevers, which are even bigger, uglier, and filthier. One of the Thieves' Guild quests pits you against a wizard who went crazy trying to convince people that Skeevers are awesome. He now plots to overrun Whiterun with a swarm of mutated venomous Skeevers. Interestingly, it seems that Skeevers aren't always bad either. The owner of the Winking Skeever inn in Solitude named the inn in memory of his beloved childhood pet Skeever.
Rat Simulator has you playing as one. Your mission in this game is to run around from house to house eating all the food, spreading disease, and avoiding the human residents who will summon flame-shooting exterminators if they catch you.
Micah Bell from Red Dead Redemption 2 has rats as his Animal Motif. While he doesn't look like one, his complete lack of ethics and moral standards as well as him betraying the Van Der Linde gang to the Pinkertons by ratting them out all embody personality traits often associated with rats. For bonus points, you can see a rat scampering around his hideout at the end of the game.
The Donkey Kong Country series of video games has rat enemies in the second and third games: Neek in the second, and Sneek in the third. Both of them are very weak and non-threatening, but Sneek's got an edge over Neek when you're playing as Ellie the Elephant: if she sees them, she'll panic and run away from them, potentially endangering you if you're close to any hazards.

Web Comics

Inverted in Digger, in which sacred rats assist the keepers of the temple library and protect the books from gnawing insects. "Mousie", conversely, is what Ed called Digger, who is tough as nails and far from cuddly or helpless.
Norveg, Angelika's rat familiar in Our Little Adventure, completely averts this, being more level-headed than Angelika and acting as her Straight Man most of the time. Norveg does at one point complain about mice having better PR than rats even though rats are the more intelligent and compassionate species. The doctor is afraid that a rat will contaminate his office.

Western Animation

Garfield befriends a mouse. On the contrary, one of the villains in U.S. Acres/Orson's Farm is a rat.
Biker Mice From Mars: The anthropomorphic rat slavers, who are also shown to be cronies of Plutarkians in a flashback episode.
Inverted in Disney's Goliath II where the villain of the short's second act is a mouse.
Gary the Rat is about an Amoral Attorney who is such a "dirty rat" that he becomes a literal rat.
South Park: The plot of "Bass To Mouth" revolves around the kids trying to stop an evil rat named "Wiki Leaks" from posting embarrassing personal stories about them online.
- Though since Wiki Leaks is the brother of Lemmiwinks the gerbil, the kids probably just got his species wrong.
Rattrap from Transformers: Beast Wars and Beast Machines. Not evil, but easily the weaseliest member of the Maximals.
The Animals of Farthing Wood have a whole swarm of rather cartoonishly evil rats, considering the otherwise more realistic tone of the show. The rat king, Bully, displays all the stereotypical traits you'd expect a fictional rat to have: he's sneaky, boastful, ruthless, filthy, and cowardly, and his followers aren't much better.
Ratty from Mr. Bogus.

Real Life

This trope is averted in real life. Rats are actually friendlier, more easily trained, and less likely to bite than mice are, and thus make much better pets than mice do. Anyone who has worked in a pet shop can attest to this. While a mouse that is regularly handled can become quite friendly, other mice tend to be jittery and sometimes aggressive. Rats, on the other hand, are friendly and inquisitive right off, and quickly learn that a human arriving means it's time for food or play. Experiments have shown that rats are one of the few animals besides humans and higher primates proven to have a sense of compassion.
Completely and utterly reversed by Rapemouse.
Inverted by the HeroRATS: Giant Gambian pouched rats which are trained to sniff out land mines in their native Africa, thus allowing thousands of refugees in war-ravaged regions to safely reclaim their farms.
Rats killing mice is Truth in Television, usually for food. They will not kill mice if they are raised and are familiar with them, however.
Nazi propaganda famously equated Jews with rat infestation.