Dola from Castle in the Sky. She's a crusty, tough-talking old lady who is abrasive, bossy, and even controlling of her boys. She even tries to kidnap Sheeta (and steal her crystal) at the beginning of the movie. Later on, she grudgingly agrees to let Pazu help her save Sheeta and agree to take them aboard her ship. (While she's playing chess with her husband, who questions her about her affections for the kids, her response is, "Whaddaya mean by that, ya old fool?! I'm after treasure. That's all." Deep down, however, she's actually a softhearted person who comes to admire Pazu and Sheeta for their loyalty toward each other. (She does a brief double-take, though, when she overhears Pazu telling Sheeta that Dola is "much nicer than she pretends to be.")
Muta from The Cat Returns is literally called a Jerk with a Heart of Gold at one point. He fits the build exactly. He has to be coaxed into helping others for selfish reasons, but for friends he's willing to fight an entire kingdom.
Kristoff in Frozen is socially awkward and brutally honest with people, and when he helps Anna on her adventure, he becomes exasperated with her antics. After a while, he genuinely starts to care for her and even falls in love with her.
Mushu in Mulan as his original intentions was to obtain a high position among the guardians. Over the course of the film, he becomes protective and supportive of Mulan. In Mulan 2, he even tries to destroy Mulan's relationship with Shang only to be the one to rescue Mulan from an unwanted marriage and prevent an upscale war.
In Shrek, the title character plays up his bad reputation to keep others off his land. But he ends up risking his life to help not only the Damsel in Distress, but hundreds of refugees as well.
To an extent, Snow White in the third film as well. She does come off as arrogant and lazy, but willingly joins Fiona and the rest of the princesses in battle against Prince Charming.
Mr. Potato Head from Toy Story. In the first movie, he was a jerk, but in the second and third movies, he improves.
John Silver in Treasure Planet, who also happens to be the Big Bad. Sacrifices the treasure he seeked to save the hero. In returns keeps his freedom.
Live Action Films
Though all the guardians in Guardiansofthe Galaxy are this to a certain degree, Rocket takes the grand prize. He starts out mocking the Xandarians and basically telling everybody how much of a rip he doesn't give about them, but when things get bleak he ultimately puts his life on the line to save all the people he said he didn't care about. Also, there's his friendship with Groot, which culminates in him sobbing over Groot's apparent death.
Ellen Ripley, the protagonist of the Alien films, was intended to come across stiff and unlikable in the first film, and also comes across as cynical and bitter in the sequels. However, she is without a doubt a heroic and selfless person, and one of the most glorious and well-known examples of Mama Bear in all fiction.
Bill Sampson in All About Eve is direct, acerbic, and unsentimental, but he genuinely loves Margo, and remains faithful to her even when she's making him miserable.
Both Gordon and Jackie from A Shot At Glory are abrasive to different people: Gordon to his family and Jackie to just about everyone except his son. Both are nice guys underneath it all.
Steve Stifler in American Pie eventually makes the transition into this in American Wedding.
Brain Donors: Roland T. Flakfizer might be a money-seeking Ambulance Chaser, but he's sincere about pairing up the star-crossed dancers Alan and Lisa.
Gary King: He is childish and irresponsible, yet he will stand for the other Four Musketeers.
Kar (Seann William Scott) in Bulletproof Monk is a common pickpocket who steals wallets from random passersby and mouths off to people. However, he not only jumps to help the titular Monk save a child about to be run over by a subway train, but also gives a hot dog to a homeless man, and helps the old Mr. Kojima. No wonder the Monk is seriously considering training Kar to be his replacement.
Casablanca: Rick Blaine sticks his neck out for nobody.
Dean in Cedar Rapids. He might be abrasive and loud with a bit of a drinking problem but he cares deeply for his daughter and friends.
In Clueless, Cher's father Mel is a tough, feared stony divorce lawyer who can make his maid scurry away in fear just by entering the room. However, he's also a devoted father not only to his daughter Cher but to Josh, his stepson from a previous (failed) marriage to whom he remains a loyal father-figure and mentor despite the fact that they have no blood relation together.
In Dead Air, Radio DJ Logan Burnhardt and his on-air sidekick Gil enjoy teasing and even insulting their more colorful callers, however both seek to do everything they can to help the citizens when the crisis starts, with Logan manning the airwaves to give advice to the survivors who are listening and Gil volunteering to venture out on his motorcycle to save Logan's wife.
Sgt. Sean Dignam of The Departed is a good example of this trope. He is incredibly abrasive to pretty much everyone, but at the end of the film after being dismissed from the case, he found Sullivan and brought him to justice showing that he is a dedicated cop and one of the most respectable characters in the whole movie.
In the Doctor movies, Sir Lancelot Spratt is blustery, arrogant, and insulting. Yet he goes out of his way to advance Dr. Sparrow's career (in Doctor In The House, he talks the school's president out of expelling Sparrow; in Doctor At Large, he allows Sparrow to work with him in surgery in spite of Sparrow's missteps).
And Kong, who spent most of the movie antagonizing Francis. Upon seeing that his mate was murdered horribly, he began to mourn for her and managed to stop being such an ass to Francis.
Stathis Borhans in the 1986 remake of The Fly is probably this trope personified. At first he is a sleazy, jealous, jilted ex-lover of the protagonist's love interest, but after a certain mishap involving a housefly and a teleporter, he becomes a Big Damn Hero and storms into the lab of the man-monster to save the woman he still loves. It does not end well for Stathis.
In 50/50, Kyle acts like a boorish jerk, but sticks by Adam's side throughout the movie.
Forrest Gump: Lieutenant Dan in the movie, and perhaps surprisingly to some, Forrest in the original novel.
There's a reason why Gamera is also known as the "Friend to All Children". This fire-breathing turtle has a soft-spot for kids and will do anything to keep them safe, even put his life on the line. Of course, his attack on Tokyo in the first film causes adults to fear the monster.
Godzilla is not only a city destroying monster, he's also a loving and devoted father. And he's also fiercely loyal to his friends and will come to their aid whenever they are in danger.
Walt Kowalski, the main character of Gran Torino is one racist son of a bitch, but we forgive him for it because he's actually a decent guy deep down toward the people against whom he's racist.
Phil from The Hangover, who despite his abrasive personality is the Only Sane Man of the trio and encourages Stu to end the abusive relationship he's in, which he eventually does at the end of the first film.
The Heat: Mullins is, for lack of a better term, a psychotic bitch, but she genuinely cares about the people in her city, her family, and Ashburn.
In the movie Hero, Dustin Hoffman's character is a misanthropic, cynical petty crook, constantly declaring that everyone is out for themselves and no one else. When a plane crashes before his eyes, a young child begs him to save his father and there's no one else to turn to, he goes into the burning wreck and rescues each person he comes across in turn - grumbling the whole time - until he finds the father - then disappears, leaving Andy Garcia to accidentally get stuck with the credit. After Garcia, a genuine Nice Guy, becomes wracked with guilt because of all the undeserved adulation, and ultimately resolves to confess in a suicide note before leaping to his death, Hoffman risks his life again in order to blackmail Garcia into tearing up the note, going back inside, accepting the credit, and keeping up all the "do-gooder" stuff, which Hoffman realizes is Garcia's natural role in life, in contrast with Hoffman's card-carrying Jerkass.
Then, at the very end, he's at the zoo when a child falls into a tiger cage and everyone else is panicking. When he realizes no one else is going to help, he begrudgingly marches over to save the day.
Iron Man 2: He may not openly display it to Tony Stark during childhood (he sent him to a private school to get him out of the house), but Howard Stark does legitimately care for Tony Stark, as evidenced by his blooper tape/hidden message.
In the film version of M*A*S*H both Hawkeye and Trapper fit this trope (far better than in the TV series). They're both insubordinate drunks, their pranks are downright mean-spirited and they show signs of being both sexist and racist. The defining moment is when they go on a golf trip, casually perform a surgery to save an infant's life against regulations, and still get out on the golf course before dark.
James, Martin's best friend in Nightwatch is a perfect example. He constantly gets Martin in trouble, even getting him thrown out of a restaurant for receiving a handjob from a prostitute , but in the end James gets handcuffed to a pipe and ends up sawing his thumb off to free himself and save Martin and Katherine .
The titular alien from Paul. Some characters describe him as being a nice guy, only incredibly rude.
The Pink Panther's Chief Inspector Jacques Clouseau is an arrogant man who believes himself to be the greatest detective in the world, or at least is determined to make sure everyone else thinks he is (Peter Sellers's interpretation). In truth, he is a chronically clumsy idiot, which is partially the result of this self-confidence, and gets him and many of the people around him in trouble. He is also genuinely on the side of good, chivalrous with women (even after being betrayed by his own wife), conducts himself with dignity as often as he can, and he simply will not give up no matter what obstacles are in his way.
Captain Jack Sparrow of Pirates of the Caribbean, having been described, as far back as the original screenplay incarnation, as having an "honest streak", which seems to serve as the pirate equivalent of a heart of gold, and also as his Achilles' Heel.
Kikuchiyo in both Seven Samurai and Samurai 7. Easily dismissed as a loudmouth with delusions of grandeur (and you wouldn't necessarily be wrong in that assessment), Kikuchiyo nonetheless is the first to jump to the farmer's cause and decides to go and help them, even though he was initially rejected for the team.
The first movie shows a great example of how J. Jonah Jameson fits this. As Jameson is chewing out Peter over whether or not Spider-Man's a hero, the Green Goblin busts into the office and demands to know who takes Spider-Man's photos. Jameson's immediate reaction is to lie and protect Peter.
Especially telling since he was at the moment being held up by his shirt collar by an obvious maniac, which has his throat constricted so that he can barely speak. He was literally risking his life to protect Peter Parker, a guy he's met a grand total of two times by this point.
The novelization looks deeper into his motives: Jameson always protects his sources, and has gone to jail twice for doing so in the past.
In the third movie, he's furious that Eddie Brock gave him fake photographs of Spider-Man, commenting that "We haven't printed a retraction in twenty years!" Not only did he fire Brock, but additionally had him shamed on the front page alongside the retraction.
Captain James T. Kirk of the new Star Trek movie fits this trope perfectly. At first, it's almost as if he wakes up in the morning and thinks of new ways to piss off any and every body he encounters. Wrecks his stepdad's car and stands up to the cop who tried to pull him over. Participates in a bar fight that some cadets start (they punched him first) because he kept hitting on Uhura (who's completely uninterested in him). Reprograms an unwinnable test, which is cheating, to prove that he can win it (by thinking outside the box). Shows no remorse when caught because he doesn't feel he's in the wrong. Indeed, Kirk demonstrates the same wheeling, dealing, and conniving traits of a Magnificent Bastard. The differences are — first, Kirk was never out to hurt anyone just for his own ends. Second, it is made clear he's only acting up because he lacks a challenge worthy of his smarts. Most importantly, he uses his cunning to save the universe. This movie states overtly what the series were more subtle about: Kirk's Jerk tendencies are also the qualities that make him The Captain we all know and love.
Billy Fish from Streets of Fire. He's an obnoxious, condescending, arrogant pencil-necked geek who views Tom Cody like the street trash the guy actually is. He thinks with his money first, and pretty much never considers how his remarks make other people feel. Except when it comes to Ellen Aim. He's in love with her, and is enough of a Determinator to walk into hell right beside Cody to get her back from the bad guys. He's even sensitive enough to realize that Ellen is still in love with Tom, and is willing to step back because he just wants Ellen to be happy, and if that means she's with Tom, then she's with Tom.
Terminator: John Connor, at least in the second film. He's a mouthy, arrogant little punk who steals from ATM machines and has no respect for authority. He even gets a pair of men beaten up by the T-800for calling him a little dipshit. That said, he has the utmost respect for human life, refusing to let the T-800 kill anyone (despite the problems this presents later), risking his life to save Sarah, and preventing her from killing a man even though it would prevent the impending apocalypse.
Macready in The Thing (1982). He blows up an expensive computer for no reason other than it beat him at chess, isn't even sad at the death of Bennings, which was partly his fault for bringing the Norwegian thing back to base, threatens to kill Nauls just because he showed them evidence he was a thing, holds the entire team hostage and kills Clark. However, when Norris has a heart attack, he orders them to untie the doctor, even though there is a high chance he could be a thing, only holds the team hostage because they were trying to murder him, seems concerned when Bennings is shot in the leg, seems very reluctant to shoot Childs when he protests and tells Mac to shoot him, and at the end he is willing to sacrifice his life to stop the thing. He also forgets his grudge with Childs, as they both sit in the freezing snow, knowing they can't survive.
Charlotte Mearing from Transformers: Dark of the Moon may give the Autobots and Sam a hard time but unlike Galloway she clearly has respect for them and later apologizes to Sam for dismissing his claims and ultimately assists them in the final battle.
The Wreckers are described as "assholes" and don't get along with humans. But they ultimately stay behind to help the Autobots fight off the Decepticons. Their leader even says "We ain't going nowhere".
The movie Waitress has two: grumpy diner manager Cal and grumpier diner owner/crotchety old man Joe. Both turn out to be fairly nice guys.
In Who Framed Roger Rabbit, Eddie Valiant is shown to be quite a jerk towards Toons because of his old grudge. He's generally mean, sarcastic and filled with anger, so God help you if you hint that he works for Toons. But, however, if you can get to a contact with him, he'll stick with you until the end and you'll find out that he's a nice guy after all, he just still brooding over his brother's death and that's why he appears to be so cold and bitter.
Teardrop in Winter's Bone starts begins the film by nearly assaulting his niece for speaking out of turn. He also casually threatens his wife with violence, which doesn't seem to be unusual in his community. Later in the film, however, he rescues his niece from possible murder, accepting responsibility for her actions in the process. In the end, he brings chicks as gifts for her younger siblings and tries to entertain them with a little banjo.
John McCone, like most of the CIA members (barring Moira MacTaggert and the Man in Black) behaving like a jerk, as well as being somewhat sexist. However, despite this, he does call out against more Jerk Ass members of the CIA whenever they are doing completely Jerk Ass things (specifically the top brass member William Stryker Sr., when he was keeping Emma Frost incarcerated in what was implied to be an unlawful incarceration practice, and when Stryker decided to have both the US and Soviet forces bombard the shores of Cuba with missiles to eliminate the mutants despite the fact that a human CIA agent [even if she's female] is present on the island with them.)
Havok bullies Hank and is generally pretty abrasive. Later, he sticks by his friends when Shaw comes, and does grow to like and respect Hank.
Tallahassee from Zombieland may act like an Ax-CrazyBlood Knight and Anti-Hero most of the time, but he does become visibly angry when Wichita crushes Columbus' hopes of finding his parents alive. And although the true extent of his loyalty to the girls is questionable, he does seem to genuinely care about Columbus and sticks by him through the whole movie.