| Marlon Brando | .... | Don Vito Corleone |
| Al Pacino | .... | Michael Corleone |
| James Caan | .... | Santino 'Sonny' Corleone |
| Richard Castellano | .... | Peter Clemenza |
| Robert Duvall | .... | Tom Hagen |
| Sterling Hayden | .... | Capt. McCluskey |
| John Marley | .... | Jack Woltz |
| Richard Conte | .... | Don Emilio Barzini |
| Al Lettieri | .... | Virgil 'The Turk' Sollozzo |
| Diane Keaton | .... | Kay Adams |
| Abe Vigoda | .... | Sal Tessio |
| Talia Shire | .... | Connie Corleone Rizzi |
| Gianni Russo | .... | Carlo Rizzi |
| John Cazale | .... | Fredo Corleone |
| Rudy Bond | .... | Don Carmine Cuneo |
| Al Martino | .... | Johnny Fontane |
| Morgana King | .... | Mama Corleone |
| Lenny Montana | .... | Luca Brasi |
| John Martino | .... | Paulie Gatto |
| Salvatore Corsitto | .... | Bonasera |
| Richard Bright | .... | Al Neri |
| Alex Rocco | .... | Moe Greene |
| Tony Giorgio | .... | Bruno Tattaglia |
| Vito Scotti | .... | Nazorine |
| Tere Livrano | .... | Theresa Hagen |
| Victor Rendina | .... | Don Philip Tattaglia |
| Jeannie Linero | .... | Lucy Mancini |
| Julie Gregg | .... | Sandra Corleone |
| Ardell Sheridan | .... | Mrs. Clemenza |
| Simonetta Stefanelli | .... | Apollonia Vitelli Corleone |
| Angelo Infanti | .... | Fabrizio |
| Corrado Gaipa | .... | Don Tommasino |
| Franco Citti | .... | Calo |
| Saro Urzì | .... | Vitelli |
| Max Brandt | .... | Extra in Furniture-Moving Scene (uncredited) |
| Tybee Brascia | .... | Dancer in wedding scene (uncredited) |
| Carmine Coppola | .... | Piano Player in Montage (uncredited) |
| Gian-Carlo Coppola | .... | Baptism Observer (uncredited) |
| Italia Coppola | .... | Extra (uncredited) |
| Roman Coppola | .... | Boy on Street Who Attended Funeral (uncredited) |
| Sofia Coppola | .... | Michael Francis Rizzi (uncredited) |
| Don Costello | .... | Don Victor Stracci (uncredited) |
| Gray Frederickson | .... | Cowboy on the Set at Woltz's Studio (uncredited) |
| Ron Gilbert | .... | Usher in Bridal Party (uncredited) |
| Anthony Gounaris | .... | Anthony Vito Corleone (uncredited) |
| Joe Lo Grippo | .... | Sonny's Bodyguard (uncredited) |
| Sonny Grosso | .... | Cop outside Hospital (uncredited) |
| Louis Guss | .... | Don Zaluchi (uncredited) |
| Merril E. Joels | .... | Toll Both Collector (uncredited) |
| Randy Jurgensen | .... | Sonny's Killer #1 (uncredited) |
| Peter Lemongello | .... | Singer (uncredited) |
| Tony Lip | .... | Wedding Guest (uncredited) |
| Frank Macetta | .... | (uncredited) |
| Lou Martini, jr. | .... | Boy at Wedding (uncredited) |
| Father Joseph Medeglia | .... | Priest at Baptism (uncredited) |
| Carol Morley | .... | Night Nurse (uncredited) |
| Rick Petrucelli | .... | Man in Passenger Seat (uncredited) |
| Burt Richards | .... | Floral Designer (uncredited) |
| Sal Richards | .... | Drunk (uncredited) |
| Tom Rosqui | .... | Rocco Lampone (uncredited) |
| Nino Ruggeri | .... | Mobster at Funeral with Barzini (uncredited) |
| Frank Sivero | .... | Street Extra (uncredited) |
| Filomena Spagnuolo | .... | Extra in Wedding Scene (uncredited) |
| Joe Spinell | .... | Willi Cicci (uncredited) |
| Gabriele Torrei | .... | Enzo the Baker (uncredited) |
| Nick Vallelonga | .... | Wedding Party Guest (uncredited) |
| Ed Vantura | .... | Wedding Guest (uncredited) |
| Matthew Vlahakis | .... | Clemenza's Son (uncredited) |