- Marlon Brando as Vito Corleone: crime boss and patriarch of the Corleone family
- Al Pacino as Michael Corleone: Vito's youngest son
- James Caan as Sonny Corleone: Vito's eldest son
- Richard Castellano as Peter Clemenza: a caporegime in the Corleone crime family, Sonny's godfather
- Robert Duvall as Tom Hagen: Corleone consigliere, lawyer, and unofficial adopted member of the Corleone family
- Sterling Hayden as Captain McCluskey: a corrupt police captain on Sollozzo's payroll
- John Marley as Jack Woltz: Hollywood film producer who is intimidated by the Corleones
- Richard Conte as Emilio Barzini: a crime boss of a rival family
- Al Lettieri as Virgil Sollozzo: an adversary who attempts to pressure Vito to get into the drug business, backed by the Tattaglia family
- Diane Keaton as Kay Adams-Corleone: Michael's girlfriend and, later, second wife
- Abe Vigoda as Salvatore Tessio: a caporegime in the Corleone crime family
- Talia Shire as Connie Corleone: Vito's only daughter
- Gianni Russo as Carlo Rizzi: Connie's abusive husband
- John Cazale as Fredo Corleone: Vito's middle son
- Rudy Bond as Cuneo: a crime boss of a rival family
- Al Martino as Johnny Fontane: a singer and Vito's godson
- Morgana King as Mama Corleone: Vito's wife
- Lenny Montana as Luca Brasi: Vito's enforcer
- Johnny Martino as Paulie Gatto: a soldier in the Corleone crime family
- Salvatore Corsitto as Amerigo Bonasera: the undertaker who asks for a favor at Connie's wedding
- Richard Bright as Al Neri: the soldier in the Corleone crime family who becomes Michael's enforcer
- Alex Rocco as Moe Greene: a Jewish mobster and Las Vegas casino proprietor
- Tony Giorgio as Bruno Tattaglia
- Vito Scotti as Nazorine
- Tere Livrano as Theresa Hagen: Tom's wife
- Victor Rendina as Philip Tattaglia: head of the Tattaglia crime family and prostitution crime boss
- Jeannie Linero as Lucy Mancini: Connie's friend and Sonny's mistress
- Julie Gregg as Sandra Corleone: Sonny's wife
- Ardell Sheridan as Mrs. Clemenza
Other actors playing smaller roles in the Sicilian sequence are Simonetta Stefanelli as Apollonia Vitelli-Corleone, Angelo Infanti as Fabrizio, Corrado Gaipa as Don Tommasino, Franco Citti as Calò and Saro Urzì as Vitelli.[7][8]
