This is great

Let me try to name some

African Americans:
CJ (GTA:SA)
Big Smoke (GTA:SA)
8-Ball (GTA III/LCS)
Ryder (GTA:SA)
Franklin (GTA V)
Officer Tenpenny  (GTA:SA)
Lamar (GTA V)
Playboy X (GTA IV)
Sweet (GTA:SA)
Dwayne Forge (GTAIV)
Gerald (GTA Online)
OG Loc (GTA:SA)

Irish Americans:
Derrick McReary (GTA IV)
Francis McReary (GTA IV)
Gerald McReary (GTA IV)
Patrick McReary (GTA IV/V)
Kate McReary (GTA IV)
JD O'Toole (GTA:LCS)
??? (Forgot, GTA IV)
??? (Don't recognise)
??? (Don't recognise)
??? (Don't recognise)

Italian Americans:
Jimmy Pegorino(GTA IV)
Joey (GTA III)
??? (Forgot)
Jon Gravelli(GTA IV)
Ray Boccino (GTA IV)
??? (Don't recognise)
Salvatore Leone (GTA III/SA/LCS)
Sonny Forelli (GTA VC)
Tommy Vercetti (GTA VC)
Toni Cipriani (GTA III/LCS)

Mexican Americans
Andreas Sanchez (GTAV)
Catalina (GTA III/SA)
Cesar (GTA SA)
Agent 14 (GTA Online) - Not sure???
Taliana Martinez (GTAV)
??? (Don't recognise)
Officer Hernandez (GTA SA)
Madrazo (GTA V)
??? (Don't recognise)
??? (Don't recognise)
Madrazo's Wife (GTA V)
T-Bone Mendez (GTA SA)

Just filled in a few blanks :)