The Colombian Cartel are a Colombian drug cartel co-led by Catalina and Miguel. First arriving in 1998, they quickly gained control of parts of Staunton Island and Shoreside Vale. They heavily involved in the drugs trade and are known to deal with the Uptown Yardies. Their main enemies are the Leone Family and the Yakuza.
The Diablos are a Puerto Rican street gang led by El Burro and are based in Hepburn Heights, Portland Island. They arrived in 1998 but, due to their limited fire power, could only gain control of one district. Three years later, the gang still has limited fire power, however, they continue to hold onto Hepburn Heights. They are arch rivals of the Uptown Yardies.
The Forelli Family, possibly led by Mike Forelli, is the smallest organization in Liberty City. In the 1980s the Forelli Family had been a major force in the city, but during 1998 saw their influence greatly reduced due to Toni Cipriani and the Leone Family. By 2001, their only territory is Marco's Bistro in Saint Mark's. They are the only gang in the game, which the gang members can not be seen walking on streets.
Led by Salvatore Leone, the Leone Family have been a force in Liberty City longer than any other gang. They are based on Portland Island, in particular Saint Mark's, but also have interests in the Red Light District, Chinatown and Trenton. They had previously controlled more of the city, but in 1998 saw their influence greatly reduced. They have a fierce rivalry with the Triads.
The Southside Hoods are an African-American street gang led by D-Ice and are based in the poorer areas of Shoreside Vale, ( appearing more in Wichita Gardens ). They arrived in the city in 1998, however divisions began to show. Differences began to show and the gang split into two sub divisions, the Red Jacks and the Purple Nines. Despite their differences, they continue to work together. After the mission Rumble, the Purple Nines are permanently wiped out from the game, meanwhile the Red Jacks continue to walk their turf on the streets.
The Triads are a Chinese criminal organization that arrived in the city in 1998, with help from the Sicilian Mafia. They control the Chinatown area of Portland and are the enemies of the Leone Family. The leader of the Triads is unknown and are involved in many criminal activities.
The Uptown Yardies are a African-Caribbean criminal organization led by King Courtney, based on Staunton Island. Their rivals are the Diablos, and are known to deal with the Colombian Cartel. They arrived in the city in 1998, and took control of some if the Forelli Family's territories, but have limited influence.
The Yakuza are a Japanese criminal organization based on Staunton Island. Since they arrived in Liberty City in 1998, their influence has fallen but are still a prominent force in the city. They are co-led by Asuka and Kenji Kasen. They are arch rivals of the Colombian Cartel, both divide their territories in Fort Staunton .
By the end of the game, 5 of the 8 gangs in the game ( Colombian Cartel, Yardies, Diablos, Leone Family and the Triads ) become hostile to the player, it means, if the player walk inside their territories, the gang members will automatically attack Claude, the most dangerous are the Leone Family, they have powerful shotguns, which can easy blow up a normal car in two shots.