The Grand Theft Auto games never take themselves very seriously (aside from maybe Grand Theft Auto IV, whose literary ambitions tackled the likes of the failed American Dream), resulting in some spectacularly hilarious characters. The protagonists usually serve as the "straight men" to the more wacky and ridiculous side characters, most of whom pepper their respective games with a unique flavor.
Of course, that's not to say that the main characters aren't funny. Some of them are enormously entertaining, and they even prove funnier than everyone around them. Regardless, every GTA game is bound to have hilarious characters, and these are the funniest of them all.
Tommy Vercetti
Vice City came at a time when the Grand Theft Auto series was expanding its story ambitions. Tommy Vercetti was the first GTA protagonist to have a personality, and the game told an expansive story about his rise to power and resulting criminal empire.
Tommy proved an exceptional protagonist, and what he lacked in complexity he more than made up for in hilarity and quotable lines. He's arguably the most enjoyable GTA protagonist in terms of humor and lighthearted enjoyment, coming at a time before the series began veering into legitimate dramatic territory.
Trevor Philips
There's no denying that Trevor Philips is the most unhinged GTA protagonist (and that's saying something). In many ways, the game is commenting on itself, offering Trevor as a meta-textual reference to its own violent protagonists and the chaos they afford creative players.
Despite his unhinged state and borderline horrifying personality, Trevor is an enormously entertaining character. He spouts many classic one liners, and his unpredictable craziness often makes for some great dark humor.
Niko Bellic
There's no denying that Niko Bellic is the most sympathetic GTA protagonist. But he might also be the funniest. For much of the game, Niko comes equipped with quite a lighthearted personality, despite his precarious situation.
He has a very unique sense of humor, complete with dry sarcasm and underhanded insults. Niko is not often impressed, and he's not afraid to voice his disappointment. Said voicing often makes for some great humor.
Brucie Kibbutz
Brucie Kibbutz is easily one of the most memorable supporting characters in Grand Theft Auto history. Brucie is a typical "bro" taken to a satiric extreme, the steroids he takes giving him unbelievable energy and aggression.
Niko pegs him as "a cool guy" (his dry sarcasm in practice), he's wildly energetic, he spouts (or, rather, yells) many great lines, and in one case, he slams his own head into the wall in a crazed bout of excitement. There's no other character like Brucie.
Love Fist
Seen and heard in Vice City, Love Fist is an exaggerated take on popular hair metal bands of the '80s. All of their names are slang for the male genitalia (Jezz, Willy, Dick, and Percy), and their drunken slurs make their already-heavy Scottish accents near indecipherable.
Love Fist doesn't appear often, but their scenes and missions are nevertheless very memorable. Of particular note is the mission Publicity Tour, which sees the heavily inebriated members of Love Fist attempting to disarm a car bomb.
Steve Scott
Like Love Fist, Steve Scott doesn't appear in much of Vice City, but all of his scenes are gold. Scott is a sleazy director of pornographic movies, complete with a sweat tracksuit and inappropriately long V-neck. Scott is absolutely obsessed with cramming a giant shark into the movie he's directing, much to the chagrin and constant annoyance of Tommy Vercetti.
Steve's lines and ridiculous need to have a giant shark is hilarious, and the comedy is largely aided by the fact that Steve is played by legendary Jaws actor Dennis Hopper.
OG Loc
OG Loc is easily one of the most ridiculous characters in the entire GTA canon. Even from his very first scene, it's obvious that OG Loc is not to be taken very seriously. He pretends he's far tougher than he actually is, and he tries way too hard to be "gangsta" (as he often puts it).
His high and squeaky voice works in contrast to his tough exterior, and no one around Loc has any respect for the man. He also harbors delusions of grandeur, believing himself a rap genius; despite the protests of nearly everyone around him, including a random man he meets in the washroom.
The Truth
The Grand Theft Auto series loves to satirize, and stereotypical stoners are the target of The Truth. The Truth is every hippie stereotype rolled into one and taken to hilarious extremes. For one thing, he refers to himself as The Truth.
He is also an intense conspiracy theorist, he wears a headband and sports long hair, he speaks in that slow "stoner voice" akin to Tommy Chong, he owns a marijuana farm, he uses phrases like "far out, man," and he drives a ridiculously colorful hippie van.
Roman Bellic
Roman Bellic is funny not through the things he says (although he does say some pretty funny things), but through his general sad-sack demeanor. Roman isn't stupid so much as he intentionally deludes himself into thinking that things are better than they are, and this delusion often results in comic gold (not to mention some drama).
And despite his precarious situation, Roman remains optimistic and joyful, and the love he has for his cousin proves infectious. He's a ball of love, energy, and humor.
Yusuf Amir
In Grand Theft Auto IV, Playboy X describes real estate developer Yusuf Amir as "serious" and "overworked." That is definitely not the man the players meet in The Ballad of Gay Tony. In fact, Yusuf might just be the most carefree and hilarious character in the entire Grand Theft Auto franchise.
Like Roman, Yusuf is lively, and this energy proves joyously infectious. He also has a penchant for using American phrases like "let's bounce" incorrectly or placing them out of context, and it proves both uproarious and adorable.