Artistic License - Gun Safety: When Vincent, an experienced hitman, is talking with Marvin, he rests his hand on the edge of the seat, his pistol pointed straight at Marvin with his finger still on the trigger. When Jules hits a bumpnote this is what Vincent blames it on, at least; Jules tells him "the car didn't hit no motherfuckin' bump!", Vincent accidentally fires the weapon, shooting Marvin in the face. Even after the accident, Vincent doesn't remove his finger from the trigger; he continues waving it around as though the gun had nothing to do with the mess in the backseat.
Badass: Subverted. While he initially comes off as your typical stoic, smooth-as-ice hitman, as the film progresses Vincent proves to be a useless, idiotic person who causes far more problems than he solves and is simply too strung out on heroin to let anything faze him. Alongside Jules, a legitimate badass, he manages to appear competent, but on his own it becomes all too obvious that he relies on his partner to do all of the work for him and simply is stoic because he's strung out of his mind on heroin.
Bumbling Sidekick: To Jules. Notably, Vincent's incompetence gets him killed barely a day or two after Jules retires.
Calling Your Bathroom Breaks: Vincent always crudely announces his need to go, which helps to differentiate him from his more professional counterpart, Jules. It also creates some incongruity with his character, being a professional hitman in a suit and tie.
Deconstruction: Of the standard crime thriller protagonist. He's cool, calm and doesn't let anything faze him, but this is almost entirely because he's on heroin through most of the movie and is unaware of his surroundings. His actual skills as a hitman are highly dubious, as Jules does all of the work for the two of them while he immediately makes the situation worse whenever he actually does anything. Despite all of this, his charming charisma is enough to fool the audience into believing him to be all that he appears to be for most of them movie.
Decoy Protagonist: Initially seems to be the typical suave bad boy protagonist of the film, but the moment the nonlinear format of the movie is revealed he drops out of the spotlight almost completely. And dies abruptly and anticlimactically before the movie's end. As a character, he is also shown to be generally useless and more trouble than he's worth, making both Jules and Butch fit the protagonist role better than he does.
Dies Wide Open: When he's shot down by Butch, his eyes are still open.
The Load: He is never much more than a liability in whatever he's involved in. He fails to locate the hiding man in the bathroom while Jules is interrogating the others, accidentally shoots Marvin, gets into a pointless argument with Wolf, almost screws up Jules' peace negotiation with Pumpkin and Honey Bunny, and gets himself killed waiting for Butch.
Mauve Shirt: He seems to be Wallace's top mook since he is involved in every mission we see onscreen.
Pet the Dog: How he treats Mia offsets some of his assholish tendencies.
Ungrateful Bastard: For evidence, look at the Marvin plotline. He spends the entire time being whiny and ungrateful to the people trying to help him clean up the mess that HE caused. Jules is quick to call him out on it.
Villain Protagonist: Along with Jules. They're two hitmen working for an L.A. crimelord who mercilessly execute his partners in a business transaction in the opening.
As the Good Book Says: He's fond of (mis)quoting Ezekiel 25:17 (with a bit of his own embellishment, as only the final lines of Jules' speech, the ones about "great vengeance and furious anger," appear in the aforementioned passage) before executing someone. As he explains to another character later, he used to think it was just some "cold blooded shit" that one said to someone before "popping a cap in his ass", but he's begun to question his lifestyle after really thinking about its meaning.
The Atoner: Starts down this by the end of the film.
"The truth is, you're the weak. And I'm the tyranny of evil men. But I'm tryin', Ringo, I'm tryin' real hard to be the shepherd."
Badass: As Samuel L. Jackson's Star-Making Role Joules is shown to be a hyper competent badass who can terrify a man simply by eating a burger in front of him.
But Now I Must Go: Played with, as when Jules has a near-death and then near-life in prison moment in the same day, he decides he must leave and travel the world. Not only is he not a heroic character, but the story is told out of order.
Breakout Character: When the movie first came out Jules was overshadowed by the marketing around Vincent Vega and Travolta's Career Resurrection. Years later, Jules is seen as the most popular character from the film and even gets argued as the "true" main character.
Mauve Shirt: Not only is he Vince's partner, but he seems important enough to Marsellus Wallace that he can talk back to him.
Heel-Faith Turn: His reciting the bible was initially simply to make himself more intimidating, though when he actually takes the time to think about what he's saying he decides to become a better person.
Heel Realization: The entire final part of the movie involves Jules' realization that he was, in fact, a tool used by wicked men.
Hitman with a Heart: Believes in a higher power and is shown to be far more caring than Vincent.
Kirk Summation: He figures "Ringo" out pretty quickly and is able to talk him out of leaving the diner in peace without the briefcase.
Hypercompetent Sidekick: Vincent is a drug-addled moron who simply cannot do anything right, while Jules is a very smart, very competent professional who backs up his image with action. In fact, his not being around results in Vincent getting himself killed.
Large Ham: At many points, such as the ending and of course the infamous "Describe what Marsellus Wallace looks like!" bit.
"Why do we feel it's necessary to yak about bullshit in order to be comfortable?"
Amazon Brigade: In the TV pilot she starred in. Her character's specialty was knives. And terrible jokes.
Brutal Honesty: She doesn't have much of a filter and offers her summation of almost every situation. This is likely because her husband is a mob boss, so she's grown accustomed to not being taken to task.
Noodle Incident: When Vincent asks Mia about the story where Tony Rocky Horror was thrown out of a building for giving Mia a foot massage, Mia points out how stupid and disproportionate this is, then says that no one but Marsellus and Tony know what happened. We never find out.
The Atoner: While Butch claims not to care about killing his opponent, he mutters, "Sorry, Floyd," to the air when he hears the news. His compulsion to save Marsellus may be connected.
Anti-Hero: He is the closest thing the movie has to a good guy since he's not a criminal and saves Marsellus' life, but he's still more than willing to double cross mob bosses and at least pretends he doesn't care that he killed an opponent in the ring on accident.
Badass: He follows in his fasmily's footsteps when he takes down a series of bad guys in the persuit of his father's watch.
Badass Back: Butch slashes the pawn-shop owner with a katana, walks past him, then finishes him off by thrusting it behind him.
Enemy Mine: When Butch goes back to rescue Marsellus.
Honor Before Reason: It made more sense for Butch to just leave Marsellus behind, but the heroic exploits of his ancestors inspired him to do the right thing.
Jobber: Subverting this is what got him in trouble with Marsellus.
Katanas Are Just Better: Although to be fair, it probably was the most practical weapon there, aside from the bat. Only the shopkeeper's gun would have been better. Unfortunately, the shotgun was in the basement.
Meaningful Name: "I'm American, honey. Our names don't mean shit." The irony is that it is meaningful, since by the end of the film Butch manages to kill quite a few people...
Persona Non Grata: Marsellus revokes Butch's "LA privileges", but this was a downgraded from an earlier implication that he'd be tortured and probably killed for disobeying Marsellus. Besides, he was planning to ride off into the sunset and never look back anyway, so "never setting foot in LA again" wasn't too harsh of a condition.
Pragmatic Hero: He saves Marsellus due to personal honor, rather than any sense of obligation.
Throwing the Fight: Marsellus tries to make him do this. He thinks winning the fight and betting everything on himself is a better idea.
Token Good Teammate: The only half-decent character working for Marsellus, or in the movie's cast (with the possible exception of Jules post-character development). He does go against Marsellus' orders and kills his opponent in the ring, though that second one wasn't intentional. He does flip-flop on the victim, since he does smack talk Floyd saying if he was a better fighter he wouldn't be dead, but also says to himself "Sorry Floyd".
"Yeah, well the days of me forgetting are over, and the days of me remembering have just begun."
Affably Evil: Before holding up the restaurant, he has a rather pleasant and friendly conversation with Yolanda.
Asian Store-Owner: Ringo laments in the opening conversation about how this trope has made knocking over convenience stores nearly impossible, since many such store owners don't speak enough English to understand "Open the fucking register!" Although he never specifically refers to Asian store owners, only "foreign".
Brandishment Bluff: He discusses a borderline case about a story he heard of someone robbing a bank by walking in with a phone, and saying on the line was a little girl they were going to kill if the teller didn't hand over the money. He points out there was probably never a little girl in the first place, but it proved that you could rob a bank with nothing more than a cell phone.
Karma Houdini: He and Honey Bunny are made to give back the MacGuffin briefcase and Jules's wallet... but, other than that, they get to keep all the loot they've robbed, including the contents of the register, several of the other diners' wallets and a cell phone, and walk away entirely unharmed - while, admittedly, looking rather shook up.
Motor Mouth: He does most of the talking when he's with Yolanda but shuts up pretty quickly once he meets Jules.
No Name Given: We never do find out Ringo's real name ("Pumpkin" is Honey Bunny's pet name for him and Jules only refers to him as "Ringo" due to his English accent).
Any of you fucking pricks move, and I'll execute every motherfucking last one of ya!
Affably Evil: At least when not waving around a gun, she can be quite friendly.
Ax-Crazy: Compared to Ringo. She's ready to blow people's heads off.
Alternate Character Interpretation: Since she and Pumpkin agree at the beginning they don't want to kill anyone, it's her act during the robbery to scare people into compliance. Note how, when Jules gets the drop on Ringo, she's panicky, crying, terrified and clearly out of her depth — but despite apparently being utterly unstable and psychotic moments before, never pulls the trigger.
Beware the Nice Ones: When she's not waving a gun around psychotically screaming at people during a robbery, she seems quite bubbly, friendly and almost sweet.
Honey Bunny: When you go on like this, you know what you sound like? Pumpkin: I sound like a sensible fucking man, is what I sound like. Honey Bunny: You sound like a duck. Quack, quack, quack, quack, quack, quack, quack...
Disproportionate Retribution: Subverted. Everybody thinks that Marsellus threw somebody out of a five story window for giving his wife a foot massage, but Mia denies it ever happened. Of course, Mia is an Unreliable Narrator so the exact truth is left ambiguous to the audience.
Although, a possible explanation is that she's pregnant: mentions that she wants a potbelly, is clearly about to tell Butch something important but decides against it because he's asleep, and in the morning, mentions wanting a big breakfast, something that a woman of her size wouldn't normally say.
Inspirationally Disadvantaged: Averted. Though heavily implied to be mentally impaired (Butch teases her cruelly over this before apologizing), she's never presented as being more capable than he is on any front.
The Load: To Butch. He would have just skipped town and avoided all the trouble in his plot line, except that she accidentally left his most valued possession behind in their apartment when she packed their stuff (even though he specifically reminded her to get it). Also, when he shows up at the end, beaten and bloodied and riding a stolen motorcycle, she ignores his repeated pleas for her to hurry up and get on, and just stands there in the parking lot asking him stupid questions.
Mood Whiplash: Koons tells a harrowing story about Butch's ancestors carrying the watch. The story becomes absurd and hilariously ridiculous as he goes on, but his tone never changes. Then again, it's Christopher Walken.
Bystander Syndrome: Tries to do this when Vincent brings an overdosed Mia to his house for treatment. Vincent doesn't take no for an answer.
Erudite Stoner: He sits around his house all day in a bathrobe but he's smart enough to keep medical journals around his place in case of OD's. He also seems to be one of the more reasonable characters in the film.
The Medic: As mentioned above, he is capable of bringing people back from OD's.
Butt Monkey: In his short screen time, he's told to shut up, gets traumatized as he watches his friends die, and then he gets his head blown off by accident. Then comes the humiliation of disposing his body.
The Mole: It's implied he was Jules and Vinces' informant.
Unlucky Everydude: Like Brett, he just happened to get in over his head. What's worse is that he barely had anything to say.
Played By: Alexis Arquette
Asshole Victim: He hides in the bathroom while his partners get killed, then pops out for a surprise attack. It doesn't end well for him.
A-Team Firing: He takes the lead characters by surprise and unloads a large-caliber revolver at them, only for him to miss every shot and get gunned down after a Beat. Jules interprets this unlikely scenario as divine intervention, and decides to give up the life of a gangster and Walk the Earth.
Justified in that they were old clothes from his college days and likely not what he normally wears.
Jerkass: Understandable, given the situation he finds himself in.
Knight in Sour Armor: He's not too happy with helping Jules and Vincent out of this jam and he doesn't try to hide it.
Motor Mouth: He flies off on a tangent when Jules and Vincent show up with a dead body.
Must Have Caffeine: He swats down Jules' attempts to change the subject (after bringing in Marvin's corpse) by praising his coffee, but he can't quite resist the temptation to brag about his taste in coffee.
N-Word Privileges: Although he really shouldn't have them, under the circumstances Jules lets it slide. His wife is black, and it's implied that he and Jules go way back, so it's likely that he has enough black friends and family in his everyday life that he's been accepted into the culture and acclimated to it well enough himself. Notice how he doesn't say it in a racially insulting tone like the rednecks do, but in a more general sense.
Odd Friendship: Many people wonder why a gangsta like Jules knows a neurotic suburbanite like Jimmy. The reason...