 | Truman Capote als Lionel Twain |
 | Alec Guinness als Bensonmum |
 | Peter Sellers als Sidney Wang |
 | David Niven als Dick Charleston |
 | Maggie Smith als Dora Charleston |
 | James Coco als Milo Perrier |
 | Peter Falk als Sam Diamond |
 | Eileen Brennan als Tess Skeffington |
 | Elsa Lanchester als Jessica Marbles |
 | Estelle Winwood als Nurse |
 | Nancy Walker als Maid |
 | James Cromwell als Marcel Cassette |
 | Richard Narita als Willie Wang |
 | Fay Wray als Door Bell (archive sound) (uncredited) |
| Robert Moore | Director |
| Ray Stark | Producer |
| Dave Grusin | Original Music Composer |
| David M. Walsh | Director of Photography |
| John F. Burnett | Editor |
| Jennifer Shull | Casting |
| Neil Simon | Writer |
| Marvin March | Set Decoration |
| Ann Roth | Costume Design |
| Joe DiBella | Makeup Artist |
| Vivienne Walker | Hairstylist |
| Fred T. Gallo | Assistant Director |
| Ron Frazier | Carpenter |
| Jerry Jost | Sound mixer |
| Joseph Kite | Boom Operator |
| Tex Rudloff | Sound Re-Recording Mixer |
| Frank E. Warner | Sound Effects Editor |
| Augie Lohman | Special Effects |
| Robert Edesa | First Assistant Camera |
| Maurice Marks | Stunts |
| Norman Harris | Gaffer |
| Roger Shearman Jr. | Camera Operator |
| Mel Traxel | Still Photographer |
| Margaret Booth | Supervising Film Editor |
| Michael A. Stevenson | Assistant Editor |
| Charles Addams | Title Graphics |
| Stephen B. Grimes | Production Design |
| Roger M. Rothstein | Associate Producer |
| David Sosna | Second Assistant Director |
| George Probert | Music Editor |
| John Brice | Editorial Staff |
| Harry Kemm | Art Direction |
| Charles H. Schram | Makeup Supervisor |
| Tony Faso | Costumer |
| Agnes G. Henry | Costumer |
| Shari Leibowitz | Assistant Production Manager |
| George Rondo | Dialogue Coach |
| Richard Moran | Key Grip |
| Vince Martinez | Finance |
| Mary Malin | Assistant Costume Designer |
| Carol Shapiro | Unit Publicist |
| Frank Bueno | Producer's Assistant |
| Julia Tucker | Continuity |
| Terry E. Lewis | Property Master |
| Wayne Fitzgerald | Title Designer |
