Walter Pidgeon character Dr. Edward Morbius
Anne Francis character Altaira Morbius
Leslie Nielsen character Commander John J. Adams
Warren Stevens character Lt. 'Doc' Ostrow
Jack Kelly character Lt. Jerry Farman
Marvin Miller character Voice of Robby the Robot
Earl Holliman character Cookie
Richard Anderson character Chief Engineer Quinn
George Wallace character Bosun
Robert Dix character Crewman Grey
Jimmy Thompson character Crewman Youngerford
James Drury character Crewman Strong
Harry Harvey Jr. character Crewman Randall
Roger McGee character Crewman Lindstrom
Peter Miller character Crewman Moran
Morgan Jones character Crewman Nichols
Richard Grant character Crewman Silvers
James Best character Crewman (uncredited)
William Boyett character Crewman (uncredited)
Les Tremayne character Narrator (uncredited) (voice)
Frankie Darro character Robby the Robot (interior) (uncredited)
