Yojimbo

Yojimbo -- more correctly^{[please verify]} Yōjinbō, meaning "bodyguard" -- is a 1961 Jidai Geki directed by Akira Kurosawa, loosely based on Dashiell Hammett's novel Red Harvest. It stars Toshiro Mifune as wandering rōnin Sanjūrō, who arrives in a town beset by criminals and decides to clean the place up (apparently for fun). His method is simple, yet clever: he reduces the number of gangsters in the town by getting the two rival factions to go to war, then mops up the remainder. An enormously influential film, it has had at least two direct remakes -- Sergio Leone's A Fistful of Dollars, and Walter Hill's Last Man Standing -- as well as homages in numerous other films and television shows. It was even used as the basis of an episode of the Pokémon anime.

Tropes used in Yojimbo include:

Action Film, Quiet Drama Scene: Quite a few of these. This is one reason this movie stands the test of time so well.
Anti-Hero: Sanjūrō.
Ax Crazy: Unosuke and Inokichi.
Badass: Sanjūrō is a complete badass, and everybody comes to realize this very quickly. In fact, seeing as how his performance influenced Clint Eastwood in A Fistful of Dollars it could be said he's one of the modern Trope Makers.
- "Cooper, two coffins... No, maybe three."
Bad Cop, Incompetent Cop: The local constable is useless and venal, and attempts to get a finders fee for recommending that Sanjūrō join one side of the gang war.
Batman Gambit: Sanjūrō is able to destroy the two rival gangs by exploiting their leaders' personalities and the fact that both of them desperately want his skills.
Bodyguard: Pretty much required in a work whose title translates as "Bodyguard". Kuwabatake Sanjuro is the ronin who the local crime bosses want to hire as their private bodyguard.
Character Tics: Sanjūrō has a habit of keeping one hand inside of his clothing and twitching his shoulders. The idea behind this is that he's like a wolf/dog and has fleas- making him a character with ticks.
Chekhov's Skill: Sanjūrō is a crack shot knife thrower.
Distracted by the Sexy: Subverted, although they give it a good try.
The Ditz: Inokichi doesn't even know how to count with his fingers. He later helps Sanjūrō escape from Ushitora's gang, involuntarily.
Don't Make Me Destroy You: Sanjūrō warns three mooks that mocked him earlier. Said mooks are all sentenced to death if caught and seem quite proud of it. Sanjūrō has thus no qualms and slays them all as a demonstration of his skills and utters the aforementioned badass line about the coffins.
The Dragon: Inokichi to Ushitora, Unosuke to Ushitora.
Enemy Civil War: Sanjūrō deliberately starts one of these.
Evil Matriarch: Seibei's wife is the really nasty one in the family.
Evil Versus Evil: The status quo at the beginning of the movie. Sanjūrō's actions just turn it Up to Eleven.
Giant Mook: Kannuki the Giant. None of the other Mooks are even as tall as his shoulders and he wields a big freakin' mallet.
Gonk: Most of the bad guys except for Unosuke.
Guile Hero: While Sanjūrō is more than capable of handling open conflicts, he spends most of the movie implementing Batman Gambits against his enemies instead.
Hollywood Healing: Sanjūrō manages to heal quickly and apparently without lasting consequences after being beaten pretty badly.
- Not that quickly. It takes him at least a week if not more to fully recover.
Homage: The scene where Sanjūrō is thrown around by his face is an homage to the 1942 film version of The Glass Key.
Improbable Aiming Skills: No, guns were NOT that accurate back then. They aren't even that accurate in present day.
I Surrender, Suckers: Subverted. Unosuke is so far into his death throes that he can't even finish Sanjūrō off at point blank range.
Line-of-Sight Name: When asked what his name is, Mifune looks out over a field of mulberry trees and gives the name Kuwabatake (mulberry field) Sanjūrō (thirty-ish).
Lost Him in a Card Game: The husband in the family in the Pet the Dog example lost his wife (and their house) gambling.
Master Swordsman: Sanjūrō
Mob War
Mr. Exposition: Gonji, who lays out the whole situation in town and who everybody is to Sanjuro(and the audience).
Nerves of Steel: Sanjūrō, as best displayed during the escape scene. Even after being beaten within an inch of his life, he's still able to think clearly enough to make an effective escape.
Never Bring a Knife to a Gun Fight: Averted. Sanjūrō wins.
Pet the Dog: Sanjūrō manages to save a family that's been caught between the quarrels of the two gangs, which tends to make him less antiheroic. In order to act a little more rugged, Sanjūrō threatens them with death if they don't get the hell out of there fast enough. He does so with good reason: If they're caught, they'll likely be killed.
- Also, at the very beginning of the film, he chances to see a farmer boy quarreling with his parents; he intends to join one of the gangs, thinking that the excitement and riches are preferable to a boring life of farming and eating gruel. Near the end of the film, Sanjūrō actually has that same farmer-turned-gangster at swordpoint. Rather than cut him down, though, Sanjūrō just remarks to him that perhaps the gruel-eating life is better than this. The boy, elated at this mercy, runs off.
Playing Both Sides: Sort-of the movie's main premise. Arguably this is the codifying example as it is the most identifiable element in the remakes A Fistful of Dollars and Last Man Standing, and is oft cited as a primary influence in later works that revolve around this premise.
Psychopathic Manchild: Inokichi is somewhere between Type A and Type E.
Ronin: Sanjūrō
See You in Hell: Unosuke's final words to Sanjūrō.
Shop Keeper: Gonji, the much put-upon restaurant owner, and the cooper/coffin-maker next door.
Slasher Smile / Psychotic Smirk: Unosuke's default facial expressions.
Trigger Happy: Unosuke just seems to like shooting things...
Walking the Earth: At the beginning, Sanjūrō wanders in whatever direction a casually thrown branch suggests.
War for Fun and Profit: The casket-maker has this attitude.