Voice Actor: Steven Ogg
A 46 year old crackhead living in the deserts of San Andreas in a trailer park. He is a drug dealer and makes tons of money off of it. However, he made even more money when he was a former robber and a former best friend of Michael De Santa before they had a mess up at one of their biggest robberies. Trevor didn't get as much money as Michael did robbing, and that's why he lives in a trailer park.
Voice Actor: Ned Luke
A 48 year old rich guy living in a mansion in the upper class suburbs of Los Santos. He has a wife named Amanda De Santa and two kids named Tracey and Jimmy, who are coming of adulthood. He was a former robber who robbed with his best friend, Trevor Phillips. As stated in the bio of Trevor, the two had split up due to a big mess up during a robbery. Michael also got a lot of the money during robberies, which had got him a rich, lavish life in upper class Los Santos.
Voice Actor: Shawn Fonteno
A 25 year old guy who lives in the hood of Los Santos with his crackhead aunt named Denise Clinton. Of course, life hadn't always been like this; Franklin had lived with his parents for a large fraction of his life until their tragic passings. Due to this, Franklin had to move into a house with his Aunt and her annoying friends. Franklin also has a job where he does car re-possession.
Allies with main 3
Voice Actor: Jay Klaitz
A 53 year old man who lives in the southern, low class end of Los Santos. He is not just a normal resident there though as he is the mastermind behind almost every robbery committed by Trevor, Michael and Franklin. He has to maneuver around in a wheelchair due to wasting disease, which in short destroys all muscles in a body if they are overused.
Voice Actor: Gerald 'Slink' Johnson
A 26 year old very tall (6 foot 7) thug who lives in the hood of Los Santos nearby Franklin. Lamar and Franklin are great friends and have been since they were children. Lamar works with car re-possession along with Franklin, and has dreams to become one of the toughest and scariest thugs in all of Los Santos.
Voice Actor: Julian Gamble
A 55 year old FIB (FBI in GTA) agent who works with Michael, Trevor, and Franklin as an insider for the FIB. He helps the three main characters basically from not being killed by the FIB or police, and in return for this, he sends the three on missions for the FIB.
Against main 3
Voice Actor: Alfredo Huereca
A 68 year old very rich guy living in the upper class of Los Santos. He has many properties due to his drug business. Early in the game, Michael and Franklin rip one of his houses support beams off to collapse it because Michael thought that the guy his wife was cheating on lived there. Little did Michael know that this would be a grave mistake, as it was Martin's house. Once Martin found out, he threatened to kill Michael and his family if he didn't get paid back for the house, which sets up the first heist in the game, the Jewel Store Job.
Voice Actor: Jonathan Walker
A 51 year old extremely rich guy living in the upper class of Los Santos on a cliffside house. He works with Steve Haines who is a corrupt FIB agent and really wants to put an end to Trevor, Michael and Franklin , but mostly just wants to end Michael. However, this end doesn't mean just to put the three, or just Michael into jail, it means to kill all of the three or kill just Michael.
Voice Actor: Robert T. Bogue
A 38 year old corrupt FIB agent who is strongly against Dave Norton's partnership with Trevor, Michael, and Franklin. Like Devin, Haines wants to put an end to the main 3 characters by killing them, but he mostly wants to put an end to Trevor.