 | Richard Anderson als Dr. Paul Mallon |
 | Elaine Edwards als Tina Enright |
 | Adele Mara als Maria Fiorillo |
 | Luis van Rooten als Dr. Carlo Fiorillo |
 | Jan Arvan als Police Insp. Renaldi |
 | Felix Locher als Dr. Emanuel |
| Gar Moore als Dr. Enricco Ricci |
| Bob Bryant als Quintillus Aurelius |
 | Morris Ankrum als Narrator (unconfirmed) |
| George Sawaya als Tony |
| Edward L. Cahn | Director |
| Jerome Bixby | Screenplay |
| Kenneth Peach | Director of Photography |
| Edward Small | Executive Producer |
| Grant Whytock | Editor |
| Ira Anderson Jr. | Special Effects |
| Robert E. Kent | Producer |
| Layne Britton | Makeup Artist |
| Herman N. Schoenbrun | Set Decoration |
| Charles Gemora | Creature Design |
| Kay Shea | Hairstylist |
| Gerald Fried | Original Music Composer |
| William Glasgow | Art Direction |
| Robert G. Carlisle | Sound Effects Editor |
| George Rutter | Script Supervisor |
| Max Frankel | Property Master |
| Einar Bourman | Wardrobe Master |
| Vou Lee Giokaris | Wardrobe Master |
| Frank Webster | Sound |
