Sgt. James Conover / Major Harold Giles
Professor Hebbel / Emmett Balfour
Paul Cameron / Trent
Adam Ballard / Louis Mace
Chief of Staff / Coulter
Fred Severn / Coroner Leland
Mr. Terrence / David Hunt
Detective Lt. Runyan / Dr. Paul Fredericks (uncredited)
Gen. Benton / Philip Exeter Dundee
Budge / Dr. Paul Pollard
Randolph E. Branch / New Sentry
Dr. Williams / Lt. Rupert Lawrence Howard (uncredited)
Lincoln Russell / Ben Fields
Capt. Terrence Ralph Brookman / Harvey Kry Jr.
Chino Rivera / General Juan Mercurio
Aabel / Dr. Block
Navigator Dexter / Policeman
The Mikie / Thetan (uncredited)
Richard Bellero / Andro
Ann Barton / Yvette Leighton
Ann Pearson / Prof. Stephanie Linden
Dr. Sui-Lin / Akada
Luis B. Spain / Dave Crowell
Henry Castle / Galaxy Being (as Wm. O. Douglas)
