| Martin Landau |
Rollin Hand (76 episodes, 1966-1969) |
| Barbara Bain |
Cinnamon Carter (76 episodes, 1966-1969) |
| Greg Morris |
Barney Collier (169 episodes, 1966-1973) |
| Bob Johnson |
Voice on Tape (158 episodes, 1966-1973) |
| Peter Lupus |
Willy Armitage (154 episodes, 1966-1973) |
| Peter Graves |
James Phelps (143 episodes, 1967-1973) |
| Steven Hill |
Daniel Briggs (28 episodes, 1966-1967) |
An elite covert operations unit carries out highly sensitive missions subject to official denial in the event of failure, death or capture.