In the film inspired by Jonathan Harr's A Civil Action Jerome Facher, played by Robert Duvall is an eccentric old lawyer, who is a huge baseball fan, to the point of playing with a ball during a conference call with a co-defendant's attorney in a serious case, always uses an old briefcase, with a cartoon character sticker on it, which keeps breaking up and that he keeps repairing with huge amounts of duct tape, even in the courtroom during an hearing. But, believe us, he is also the kind of lawyer every sensible defendant would like to have on his side.
The Man with Two Brains. Dr. Hfuhruhurr literally wears them going into surgery. It's a practical joke, but it's a Visual Pun as you discover that is exactly the kind of doctor he is. C'mon, folks - screw-top brain surgery?
Kuryu, the main character of Japanese movie Hero (based on the TV series) is almost literally a Bunny Ears Lawyer. He constantly wears almost-aggressively casual clothes while his contemporaries wear suits, he indiscriminately buys random items from the shopping channel, and spends the whole movie trying to learn Spanish simply because he inadvertently ordered a book in that language. His quirks are overlooked however, partly because he is a cunning and successful lawyer, but mostly because his co-workers are all subtly quirky too.
Glen Whitmann, in Transformers, is a brilliant computer hacker, who may have ADHD and exhibits extremely erratic, perhaps sociopathic behavior. Apart from a lack of basic manners and some sort of unspecified paranoia, his great passions in life appear to be video games and getting into places he does not belong. Which could honestly be said of 90% of computer hackers. Hacking is, after all, all about getting into places you don't belong.
Agent Seymour Simmons, who is just a smidge off his nut, but who is very good at what he does. In a bizarre subversion of this trope, his Bunny Ears-ness is implied in the novel The Veiled Threat to be the reason he isn't working for NEST.
Ace Ventura: Pet Detective is downright certifiably insane (manic episodes and schizophrenia at the least). He is also very good with animals, a highly observant and capable investigator, a decent actor, ace driver, love-machine par excellence and no slouch in a fight.
In Legally Blonde 2: Red, White, and Blonde, her awesome knowledge of fashion allows her to root out political shenanigans on Capitol Hill.
Stéphane from The Science of Sleep is completely... mad, possibly... due to his confusing dreams that keep melding with reality (that he's not entirely about to cope with). However he is a technical genius. He makes a toy horse gallop with robotic parts - rather realistically and possibly a one-second time machine. His "Disaterology" also becomes a big success.
Dr. Strangelove is a brilliant former Nazi with a severe case of alien hand syndrome - his right hand gives the Seig Heil salute without his control, and takes extreme effort to force back into his lap, and occasionally attempts to strangle him. Among other things.
Martin Riggs from the Lethal Weapon series is suicidal in the first film, and then just plain crazy after he gets over it. He deliberately plays havoc with the department's psychiatrist (and starts to make her snap), for bonus points. His near unstoppability when dealing with thugs is likely the only reason he is left on the force.
Holmes in Sherlock Holmes (2009) is a brilliant detective, but he is also quite eccentric as well as having a recurring cocaine dependency. Watson is used to this kookiness but a lot more normal.
John Mason (Sean Connery) from The Rock is a good example. Despite being considered one of the most dangerous men alive, the US government is essentially ready to give him anything he wants in order to get him to work, because he escaped Alcatraz and lived to tell about it.
The pilots in Air America are completely insane, but really good pilots.
Subverted in Smokin' Aces. There is an eccentrically sleazy lawyer. For his first scene, there is literally a costume rabbit head showing in the background. However, he proves to be completely incompetent.
The detective in Laura always plays with a handheld maze game.
Vinny in My Cousin Vinny is an acerbic Brooklyn stereotype with a mouth like a stevedore(being played by Joe Pesci, this is to be expected), but turns out to be a brilliant and tenacious opponent in the courtroom. Also, his girlfriend Lisa, an aspiring hairdresser who knows enough about cars that her testimony ends up proving the defendants' innocence.
Willie Beamen in Any Given Sunday had the habit of throwing-up at least once every match. However, he's a reasonably competent quarterback that he took over as the starting QB when the previous one was injured.
In the 2011 film Warrior: Frank Campana is known for his unusual training methods involving classical music, but damn if he gets results.
Lampshaded early in Top Gun when Stinger chews out Maverick and Goose for the umpteenth time. Maverick's lost his qualifications as section leader several times, and has a habit of making high-speed passes by control towers and atan admiral's daughter. About the only reason he hasn't been kicked out of the Navy altogether is that he's a damn good pilot.
Jimmy from Timecop is lucky he knows how to use a computer for more than just watching virtual reality porn. An alternate timeline shows us a much more serious Jimmy with no such vice.
Ahnuld's buddy Hank in The 6th Day is a goofball who lives with a robotic prostitute, but he takes his job as a helicopter pilot seriously and is more than happy to cover for Ahnuld on his birthday. He gets killed for his troubles.
Daniel Rafferty in the film Laws of Attraction. When we first see him, he's dozing in court, is scruffy, unkempt, and as we later see, works out of a ramshackle office in a rundown area of Chinatown, despite the fact that he could clearly afford better, as evidenced by his very nice apartment. But within two seconds of meeting uber-uptight attorney Audrey Woods, he wipes the floor with her and it's mentioned that he's never lost a case.
Down Periscope is all about figuring out that this trope applies even in the navy.
Commander Dodge is famous throughout the Navy for his cavalier attitude to command and his immature antics (not to mention his penis tattoo) but he is also a prime example of immature not meaning irresponsible. His goofball antics never affect his performance on the job in spite of being less than professional, he is well-liked by his subordinates, and he manages to whip a World War II-era rustbucket of a submarine and a Rag Tag Bunch Of Misfits into an effective fighting force over the course of a Montage.
Sonar, the Sonar technician has hearing so good that he's been considered a security threat. He can count money just by hearing it drop on the floor. Also, he's studying the language of whales. And he's a bit off. Nonetheless, he saves his crew from peril with all those abilities.
Nitro, the electrician and radio operator, is more than a bit off because he's absorbed so much electricity. Nonetheless, he's probably the only one capable of making the electrics on the Stingray actually work.
Even the Stingray, a World War II relic diesel submarine could count, because it's the only sub that could manage to sneak into Norfolk.
"Oddball" from Kelly's Heroes has a bazillion and nine strange quirks, not least of which is an obsession with positive thinking, but still manages to be a highly skilled tank commander.
Detectives Gavilan and Calden in Hollywood Homicide. Gavilan is a Deadpan Snarker who moonlights as a real estate broker and is being investigated for financial improprieties by Internal Affairs. Calden is an aspiring actor who fancies himself a Warrior Poet. In the film's climax, they manage to solve their case and catch the bad guys in a wild Chase Scene, while indulging their side interests at the same time.
In Ra.One, Shekar, who is quite good at his job of game designing, but incredibly spacey—to the extent that no one seems to notice when he is replaced with a robotic double incapable of comprehending sarcasm.
Dr. Newton 'Newt' Geiszler from Pacific Rim. He's loud and eccentric to say the least. If he wasn't such a competent Kaiju biologist, he'd probably get checked into a mental hospital due to his borderline-obsession with the things.
Nathan from Ex Machina, acts like a drunken frat boy around Caleb, but is smart enough to invent fully intelligent and self aware AI with durable android bodies that easily pass for human.
Michael Burry, the financial investment genius who goes around the office in T-shorts, shorts, and barefoot, constantly drumming to heavy metal music and monologuing to himself.
Ben Rickert is a retired investor with connections everywhere, and is also a paranoid survivalist who hates Wall Street.
The titular character from The Cable Guy might be pushy, obnoxious, have absolutely zero social skills, No Sense of Personal Space, and be a dangerous and vindictive sociopath, but he happens to be one hell of a cable guy. The man can find where the problem is in your cable simply by talking dirty to the walls and is able to clear up interference by doing nothing more than moving furniture. Later subverted when he was in fact fired from the cable company, countless times by using fake identities, and is now merely impersonating a cable guy.
J. Jonah Jameson in the Spider-Man Trilogy. While he's very bombastic and over the top, when he's told in Spider-Man 3 that he'll have to issue a retraction after he fires Eddie Brock Jr. for fabricating a photo of Spider-Man, he exclaims that he hasn't had to print a retraction in twenty years! Indicating he is very good as an editor-in-chief despite his sensationalist tendencies.
Me, Myself & Irene: Charlie's illegitimate but loving sons are incredibly profane and obnoxious hoods... who have incredibly superhuman intelligence. They manage to operate a helicopter... with German instructions.
Shonte Jr.: Anybody know how to fly this damn thing?
Jamaal: Motherf***r, it can't be that hard, it's just lift versus drag and rotation!
Deconstructed on Death Machine, which gives us Big Bad Jack Dante. He is one of the most horrifying man-children ever put on screen, but he's so good at creating the kind of weapons Mega-Corp CHAANK wants that the more amoral executives try to tolerate him. The deconstruction lies in that by the point the movie starts he's screwed up a bit too much for them to consider his projects practical but he's creeped them out to the point that they can't bring themselves to fire him, so protagonist Hayden Cale (the Only Sane Employee by virtue of being a Naïve Newcomer) decides that there's no advantage in having such a psycho around no matter what.
Live Forever As You Are Now with Alan Resnick: Alan is quite eccentric and strange, doing things such as forcing those who go through his program to spend five-hours looking at a mirror and go to his house so he can strobe lights in their face, and describes the Uncanny Valley with an example about putting skin on a rock. At the same time, he's an accredited computer wizard, who did at the very least come up with a way to create digital clones of himself and others.
In When Evil Calls, Detective Ringwald bears all the hallmarks of being a Defective Detective, but somehow is the only person who zeros in on the cause of the mysterious deaths plaguing Wilburn High School, despite it involving the supernatural.