Any given film noir hero. Sam Spade is probably the snarkiest of the lot, but J.J. Gittes of Chinatown gets one or two good ones.
Loach: What happened to your nose, Gittes? Somebody slammed a bedroom window on it? Gittes: Nope. Your wife got excited. She crossed her legs a little too quick.
Many characters in '30s and '40s screwball comedies, such as those played by Cary Grant, fit this trope.
Back to Sam Spade, in regards to the actor who plays him, Humphrey Bogart. Any movie with Bogie in it is guaranteed to be full of snark. His wife, Lauren Bacall, was the only one who could match him in terms of wit. Just watch any of the four movies they made together for proof.
Margo in All About Eve. "Fasten your seatbelts, everybody, it's going to be a bumpy night!" Addison perhaps even more so. Come on, he has "wit" in his last name!
Lucius Fox: ... I've come to explain to you why we're going to have to put our deal on hold. We can't afford to be seen to do business with, well, whatever it is you're accused of being. A businessman of your stature will understand.
Lau: I think, Mr. Fox, that a simple phone call might have sufficed.
Lucius Fox: Well, I do love Chinese food. And Mr. Wayne didn't want you to think we'd been deliberately wasting your time.
Trader: This a stock exchange! There's no money you can steal!
Bane: Really? Then why are you people here?
Some of Bane's lines during both of his fights with Batman fall into this.
Batman:[to Selina] You've made a serious mistake.
Bane: Not as serious as yours, I'm afraid. [Batman turns to face Bane]
Bane: Let's not stand on ceremony here.... Mr. Wayne.
When Selina meets Stryver at the bar:
Philip Stryver:[examining the print slide] Very nice.
Selina Kyle: Mmm-hmmm. Not so fast, handsome. You got something for me?
Philip Stryver: Oh, yes. [He signals to one of his guys, who locks the front doors. Selina smiles, nervously]
Selina Kyle: I don't know what you're planning to do with Mr. Wayne's prints, but, I'm guessing you'll need his thumb. You don't count so good, huh?
Philip Stryver: I count fine. [A thug cocks and puts his pistol to Selina's head] In fact, I'm counting to ten, right now.
When Bruce is dancing with Selina:
Bruce Wayne: You wouldn't want any of these folks realizing you're a crook, not a social climber. Selina Kyle: You think I care what anyone in this room thinks of me? Bruce Wayne: I doubt you care what anyone in any room thinks of you. Selina Kyle: Don't condescend, Mr. Wayne. You don't know a thing about me. Bruce Wayne: Well, Selina Kyle, I know you came here from your walk-up in Old Town, a modest place for a master jewel thief. Which means that either you're saving for retirement, or you're in deep with the wrong people. [beat] Selina Kyle: You don't get to judge me just because you were born in the master bedroom of Wayne Manor. Bruce Wayne: Actually, I was born in the Regency Room.
Selina's confrontation with Daggett, where she is coolly offended by Daggett calling her a "dumb bitch".
Olive in Easy A is definitely this. She seems to get it from her mother. As is Woodchuck Todd (her crush). And Mr. Griffith takes this trope Up to Eleven.
Brandon: "Do you wanna go out with me?"
Olive: "Brandon. You're a nice guy and all but... you're... not... "muh type"."
Brandon: "Yeah, you're not my type either."
Olive: "I know! I have a V where you'd rather see a P."
Brandon: "Olive please..."
Olive: "Brandon, just a couple of hours ago you told me you were kinsey 6 gay."
Brandon: "You said I should pretend to be straight."
Olive: "Yeah but not with me."
Brandon: "I am tormented every day at school. Just one good, imaginary fling."
Cop: "Do you know you were doing fifty in a twenty five miles per hour zone?"
Elvira: "No, but if you hum a few bars I'll fake it."
Elysium: Max to an extent. Considering what he's dealt with over his life and what comes next, anyone would be. Mouthing off to robots isn't too smart, though.
The cast of Fifty/Fifty, but especially Sam French and especially Jake Wyer.
In Finding Neverland, Charles Frohman (the producer and financier of James M. Barrie's plays) spends most of his limited time on-screen being the deadpan, snarking, sensible Foil to the more animated, optimistic, and erratic Barrie.
Deconstructed in Funny People; George and the other comedians are certainly very quick-witted, snarky and quick with a cutting comment, but it's made fairly clear that they use wit as a substitute for actually forging meaningful connections with other people, and the often hurtful nature of their comments doesn't help either.
In the movie-musical Hairspray, Penny Pingleton gets in a good one. When Motormouth Maybelle recognizes that her son has fallen in love with a white girl, she warns the two lovers, "You're gonna have to deal with a whole lotta ugly from a never-ending parade of stupid." Penny answers, "Oh, so you met my mom."
Hellboy's father, Trevor Bruttenholm, seemed this way at times. Searching for Nazis on a "deserted" island, he's told, "There's nothing on this island but rocks and sheep." When they find the Nazis, he looks at the officer in charge: "They must be here for the sheep." That must be where HB himself got his snark from.
(secret door takes them from burning building to Nazi headquarters) Henry Jones Sr.: Our situation has not improved.
Naturally, Iron Man has its titular armored hero, which then gets taken to the next level in The Avengers, and even moreso in Iron Man 3. Said film is even directed by the already-mentioned Shane Black.
Hallenbeck: Sure, sure, I know, it just happened, it could happen to anybody... It was an accident right? You tripped, slipped on the floor and accidentally stuck your dick in my wife : "Oops I'm so sorry Mrs H, I guess this just isn't my week".
"Liu, I hate this place. I'm telling you, I hate it. I'm in a hostile environment, I'm completely unprepared, and I'm surrounded by people who probably want to kick my ass. It's like being back in high school!"
"The fate of billions will depend upon you. Heh heh heh heh! ...sorry."
Walking away after telling Johnny and Sonya which of their fears will trip them up
NORRINGTON: Mr. Sparrow, you will accompany these fine men to the helm and provide us with the bearing to Isla de Muerta. You will then spend the remainder of the voyage contemplating all possible meanings of the phrase 'silent as the grave.' Do I make myself clear?
Both Nick and Roy in R.I.P.D. , and given their line of work, it comes to no surprise.
Riff-Raff: Yes... and also presumptuous of you. You see... when I said 'we' were to return to Transylvania... I referred only to Magenta and myself. I'm sorry, however, if you found my words misleading, but you see... you are to remain here... in spirit anyway.
Ed in Rubin And Ed. This is partly just his natural personality and partly a defense mechanism he created to cope with his various insecurities and his Dark and Troubled Past
Scrooge1970: The Spirit of Christmas Present, of all people. Not in the book and not in most adaptations, but in the 1970 musical Scrooge he has a ton of deadpan gems. For instance, when Scrooge says he would like to look into the window of the Cratchitt house the Spirit, inviting him by indicating with his hand, says, "It will cost you nothing—which I feel sure will be good news for you." Scrooge asks if the Cratchitts will be able to see him. The Spirit replies, "No...which I feel sure will be good news for them."
Mrs. Palmer:(talking to someone else) If only he'd gone to Combe Magna. We live but half a mile away. Mr. Palmer: Five and a half. Mrs. Palmer: I cannot believe it is that far. I can't believe it. Mr. Palmer: Try.
From Episode I, after the Trade Delegation try to kill the Jedi before even meeting them, he quips on the run. "You were right about one thing, Master. The negotiations were short."
In Episode II, he muses in a dogfight, "This is why I hate flying." And when Anakin sarcastically says "Excuse me" and jumps out of a moving speeder, Obi-Wan calmly says, "I hate it when he does that."
Also, in the arena:
Anakin: We relayed your message just like you requested, Master. Then we decided to come and rescue you. Obi-Wan:(glancing at his handcuffs and chain) Good job.
And later (also in the arena) when Anakin is worried about Padmé, Obi-Wan draws his attention to the fact that she's freed herself and has climbed to the top of her pillar: "She seems to be on top of things."
In Episode III, when the Invisible Hand begins to fragment: "Not to worry, we are still flying half a ship." And when they finally crash-land "Another happy landing."
Later, after he takes out General Grievous with precision blaster-fireObi-Wan discards the blaster simply saying "So uncivilized." (This is a reference to his earlier (later?) line in Episode IV about the lightsaber being "elegant weapon, of a more civilized age" and being "not as clumsy or random as a blaster" and it is made even funnier in the book. He spends a moment thinking of the absolute worst word in his vocabulary, a real crusher. "Uncivilized" is what he came up with.
Earlier in the fight with Grievous (in the novelization):
Grievous: I was trained by Count Dooku himself. Obi-Wan: Funny. I trained the man who killed him.
Age does not wither his snark nor the years condemn. In Episode IV, when Luke tells "Ben" Kenobi that his uncle says that Obi-Wan is dead, the Cool Old Guy assures him, "Oh, he's not dead." Then he takes a quick look at his desolate surroundings and adds, "Not yet."
In the novelizations, even his internal narration is snarky:
(while clinging to a flying assassin robot hundreds of miles above Coruscant) This is not the best idea I ever had.
Anakin Skywalker in Revenge of the Sith. When Obi-Wan points out the inadvisability of trying to clear pesky droids off his fighter's wing by shooting at them: "I agree, bad idea." (And then he does it. Although he does blow half of the fighter wing off in the process.) When asked if he can fly the Invisible Hand as it's falling toward Coruscant's surface: "Under the circumstances I'd say the ability to fly this thing is irrelevant." (And then he does it.)
His snark is even worse in the novelization of Revenge of the Sith, especially when he's killing the Separatist leaders:
Rune Haako: We surrender! Please - you're a Jedi!. Anakin: You fought a war to destroy the Jedi. Congratulations on your success.
Nute Gunray: You can't! Lord Sidious promised we'd be left in peace. Anakin: The transmission was garbled. He promised you'd be left in pieces.
Shu Mai: We were promised a reward, a handsome reward... Anakin: I am your reward; you don't find me handsome?
And, like Obi-Wan, the version of Anakin in the Clone Wars animated series is even snarkier.
Anakin may have "Taken a Level in Snark" after he became Darth Vader with a healthy dose of menace thrown in. The classic example would probably be his "I find your lack of faith disturbing" from Episode IV.
Failing hyperdrive + Princess Leia = instant snark. Actually, a lot more situations than that. Apparently, she gets it from her father.
[Luke gets shot by the remote.] Han Solo:[laughs] Hokey religions and ancient weapons are no match for a good blaster at your side, kid. Luke Skywalker: You don't believe in the Force, do you? Han Solo: Kid, I've flown from one side of this galaxy to the other. I've seen a lot of strange stuff, but I've never seen anything to make me believe there's one all-powerful Force controlling everything. There's no mystical energy field that controls MY destiny. It's all a lot of simple tricks and nonsense. Ben Kenobi:[gets up and takes a blast helmet] I suggest you try it again, Luke. This time, let go your conscious self and act on instinct. [puts the helmet on Luke, which covers his eyes] Luke Skywalker: But with the blast shield down, I can't even see! How am I supposed to fight? Ben Kenobi: Your eyes can deceive you. Don't trust them. [Watches Luke succeed in blocking the lasers] Han Solo: I call it luck. Ben Kenobi: In my experience, there is no such thing as luck.
In Episode IV (after he shoots Greedo) "Sorry about the mess." and (after he shoots a communications device) "Boring conversation anyway." Another gem from Han Solo in Episode VI, on the way to the Sarlacc's Pit while he was half-blind:
Luke Skywalker: There's nothing to see. I used to live here, you know. Han Solo: You're gonna die here, you know. Convenient. Luke: Just stick close to Chewie and Lando. I've taken care of everything. Han: Oh. Great.
C-3PO is something of a snarker in A New Hope.
C-3PO: Just you reconsider playing that message for him! (R2 beeps a question) C-3PO: No, I don't think he likes you at all. (R2 beeps again) C-3PO: No, I don't like you either. ... C-3PO: I would much rather have gone with Master Luke than stay here with you. I don't know what all this trouble is about, but I'm sure it must be your fault.
You could probably even include R2D2 on this list. While C-3PO is the only one who knows exactly what he's saying in that odd binary language of his, the viewers can get a pretty clear idea (through his partner's translations and reactions) and he can seem somewhat sarcastic at times.