| Name (Sort) | Character (Sort) | |
| •Steven Hill (1) | played | Daniel Briggs (S01) (28Eps.) |
| •Peter Graves (1) | played | James Phelps (S02-S07) (108Eps.) |
| •Martin Landau | played | Rollin Hand (S01-S03) (72Eps.) |
| •Barbara Bain | played | Cinnamon Carter (S01-S03) (67Eps.) |
| •Leonard Nimoy | played | The Amazing Paris (S04-S05) (47Eps.) |
| •Lesley Ann Warren | played | Dana Lambert (S05, as Lesley Warren) (23Eps.) |
| •Greg Morris | played | Barney Collier (132Eps.) |
| •Lynda Day George | played | Casey (S06-S07) (11Eps.) |
| •Peter Lupus | played | Willy Armitage (113Eps.) |
| •Sam Elliott | played | Dr. Douglas Roberts (S05) (12Eps.) |
| •Barbara Anderson | played | Mimi Davis (S07) (2Eps.) |
| •Bob Johnson (1) | voiced | The IMF Voice (112Eps.) |