Uncle Martin (The Martian)............ Ray Walston
Reporter Tim O'Hara................... Bill Bixby
Mrs. Lorelei Brown................. Pamela Britton
Teenager Angela Brown (1963-64)...... Ann Marshall
Mr. Burns (Tim's boss, 1963-64)... J. Pat O'Malley
Lt. Bill Brennan (1964-end)........... Alan Hewitt
The Police Chief (1965-66)............ Roy Engle
Ray Walston was mostly known as a movie actor in secondary roles before Martian, though he did have a prominent role in the 1958 fantasy "Damn Yankees," (reprising his role from the Broadway version), about a baseball fan who sells his soul to the devil to be the team's star batter.
J. Pat O'Malley was already a veteran of sci-fi and fantasy tv, having guest starred regularly in Lights Out, Tales of Tomorrow, and even himself played a lovable alien hiding from the authorities in an episode of The Twilight Zone.