Edward Connell as David Fielding (as Skip Shimer)

Barbara Hewitt as Susan Turner

Jack Woods as Asmodeus

Frank Bonner as Jim Hudson (as Frank Boers Jr.)

Robin Christopher as Vicki (as Robin Snider)

James Phillips as Reporter Sloan (as Jim Phillips)

Fritz Leiber Jr. as Dr. Arthur Watermann (as Fritz Leiber)

Patrick Burke as Doctor Branson

Sharon Gray as Nurse

Louis Clayton as Old man in cave

Norvelle Brooks as

Irving L. Lichtenstein as

James Dwion as The Orderly

Forrest J. Ackerman as Doctor on Tape Recorder (voice) (uncredited)

Jack H. Harris as Detective Harrison (uncredited)

Chuck Niles as Reporter Sloan (voice) (uncredited)

Jim Duron as The Green Giant