 | Oliver Reed als Hugh Lombard |
 | Elke Sommer als Vera Clyde |
 | Richard Attenborough als Judge Arthur Cannon |
 | Stéphane Audran als Ilona Morgan |
 | Gert Fröbe als Wilhelm Blore |
 | Herbert Lom als Dr. Edward Armstrong |
 | Maria Rohm als Elsa Martino |
 | Adolfo Celi als General André Salvé |
 | Alberto de Mendoza als Otto Martino |
 | Charles Aznavour als Michel Raven |
 | Orson Welles als Voice on Tape |
 | Naser Malek Motiee als Inspector |
 | Rik Battaglia als Rick Battaglia/Vendedor |
 | Teresa Gimpera als Maria |
 | Sepideh als Inspector's Girlfriend |
| Agatha Christie | Novel |
| Harry Alan Towers | Producer |
| Fernando Arribas | Director of Photography |
| Peter Collinson | Director |
| John Trumper | Editor |
| Harry Alan Towers | Writer |
| Erich Kröhnke | Writer |
| Alexander Grüter | Executive Producer |
| Louis Bonnemaison | Makeup Artist |
| Cristóbal Criado | Makeup Artist |
| Gabrielle Reinecke | Editor |
| Enrique Llovet | Writer |
| José María Tapiador | Production Design |
| Alain Dahan | Producer |
| Harry Benn | Associate Producer |
| Juan Estelrich March | Associate Producer |
| Ennio Nobili | Co-Producer |
| Tíbor Reves | Associate Producer |
| Bruno Nicolai | Original Music Composer |
| Carlo Rustichelli | Original Music Composer |
| Ana Criado | Hairstylist |
| Luis Criado | Assistant Makeup Artist |
| Juan Estelrich March | Production Manager |
| Ángel Sevillano | Production Assistant |
| Nicholas Wentworth | Post Production Supervisor |
| José López Rodero | Assistant Director |
| Stefano Sbarigia | Assistant Director |
| Mike Le Mare | Sound Editor |
| Peter Offer | Sound Assistant |
| Trevor Pyke | Sound Re-Recording Mixer |
| Wilhelm Schmidke | Sound |
| Ivan Sharrock | Sound Mixer |
| Emilio Ruiz del Río | Special Effects |
| Julio Leyva | Lighting Technician |
| Mario Mazzoni | Still Photographer |
| Eduardo Noé | Camera Operator |
| Javier Pérez Zofio | Assistant Camera |
| Ramón F. Suárez | Additional Director of Photography |
| Michael Crowley | Assistant Editor |
| María Luisa Pino | Assistant Editor |
| Bruno Nicolai | Conductor |
| Susanna Merry | Continuity |
| Charles Athey | Production Accountant |
