Niko Bellic
The protagonist and the character you control. He is originally from Serbia, 30 years old and sometimes speaks in Serbo-Croatian. He has come to Liberty City in search of a better life, and to find someone who has betrayed him.

Roman Bellic
Friend benefit: Car service. Call him for a free taxi anywhere in the city.
Niko's cousin. In the years since moving to Liberty City, he has built up a car service company.

Roman never seems to sleep and doesn't seem to have any preferences on where to go to build a friendship.

At 60% friendship, you can call him for his free taxi service.

Little Jacob
Friend benefit: Gun dealer. Call him up and he'll tell you where to meet him to purchase guns. He offers body armor and most weapons. Just like gun shops, the number of available items will increase as you progress through the game. Weapons excluded are basic rifle, bat, combat handgun, RPG, and basic shotgun.
Originally from Jamaica, he speaks with a very heavy Rastafarian accent. It is difficult and at times impossible to understand what he is saying. He sometimes helps out with missions.

Jacob sleeps from 4am(?) until 2pm.

He especially likes darts, drinking, and Cluckin' Bell.

At 75% friendship, you can call him to purchase guns

Brucie Kibbtuz
Friend benefit: Once befriended he can be called to pick you up in his helicopter at an open space and taxi you to another open space anywhere on the map. Also, he can set up races over the phone, but it is not necessary to befriend him for races.
Brucie is a fanatic about fitness, and routinely abuses steroids and other performance enhancing drugs. He is a friend of Roman's. Later on he gives the "Exotic Imports" side missions through e-mail (10 in total).

Brucie sleeps from midnight(?) until 8am.

Brucie highly enjoys boating, bowling, and drinking. He also enjoys expensive meals.

At 70% friendship, Brucie will offer you transportation in his helicopter.

Dwayne Forge
Friend benefit: Once befriended he can send over some of his gang for support.

Friend of Playboy X's, he was only recently released from prison. Later on you will have the option to kill him, if you don't he will become a friend.

Dwayne sleeps from 2am(?) until noon.

Dwayne likes darts, drinking, and Cluckin' bell.

Patrick McCraery
Friend benefit: Packie can provide you with a car bomb that you can use as you need it.
Associate of Elizabetha. Possible friend. Part of the McReary crime family. Becoming close friends with Packie gives access to car bombs.

Packie sleeps from 8am(?) until 4pm.

Packie especially enjoys darts and drinking.

At 75%, you can call him for the car bomb