Gary Collins (1 episode, 1998)
Ken Davis / ... (2 episodes, 1978)
Prof. Fairgate / ... (2 episodes, 1978-1979)
Colonel Vasily Zuchov (1 episode, 1974)
Bill Ryan / ... 2 episodes, 1974-1976
Dr. Michael Rhodes (25 episodes, 1972)
(segment "Love and the Seven-Year Wait") / ... (4 episodes, 1970-1973)
Capt. David Larkin / ... (2 episodes, 1968-1969)
Dave Tarrant / ... (8 episodes, 1966-1968)
Jason Adams (1 episode, 1969)
Alex Tanner / ... (2 episodes, 1965-1966)
Ned Harkness / ... (3 episodes, 1978-1980)