Roman's cousin who immigrated from Serbia and the protagonist of GTA IV. He cherishes his family and will commit crimes for their sake. He is loyal and possesses a soft heart, often helping others out of sympathy. He is a veteran of the Yugoslavian Army.

A Serbian immigrant and Niko's cousin. A boaster who currently owns and operates a taxi company. His gambling addiction has left him pursued by Albanian loan sharks due to his mounting debts.

A Jamaican immigrant and Niko's friend. A member of the Jamaican Yardies, he assists Niko whenever he faces trouble.

A Jewish-American and Niko's friend. A fitness addict whose brain seems to be made of muscle, he met Roman online and became friends with Niko. Likely due to steroid abuse, he is a comedic character who frequently behaves erratically.

A Russian immigrant and a member of the Faustin Bratva. Though Niko's business partner, he is highly suspicious and prone to betraying others, harboring a grudge against Niko. He served in the Soviet Air Force alongside Mikhail Faustin.

The boss of the Russian Red Mafia, the Faustin Bratva. He suffers from severe anger issues, treating others violently or killing them when enraged. He served in the Air Force with Rascalov, who remains his close associate.

The boss of the Pegorino family, an Italian-American mob. He makes his money through arms smuggling. His goal is to restore his organization to glory, but his irritable nature leads him to mistreat his subordinates.

A cunning member of the Pegorino family. He assists Niko and assigns him missions related to diamonds. He serves as a caporegime within the organization.

An Irish-American immigrant and Niko's friend. His daily routine consists mostly of drinking until he passes out. He is relatively short. As a reckless opportunist living only for the next drink, he has a violent temperament and a foul mouth.

The boss of the Gambetti family, the largest criminal organization in Liberty City, though he is currently bedridden in a hospital. He is the undisputed king of the underworld, to the point that mayors and senators visit his bedside. He exacts brutal revenge on anyone who crosses him.