Peter Graves as Jeff Knight

Eileen Dietz as Dana

Paulette Breen as Lena

Frank Ashmore as George Walker

Dick Sargent as Dr. Jameson

Zale Kessler as Dr. Nelson

William Bufkin as Clone

Tony Haig as Jack

Boyd Holister as Senator

Keenan Wynn as Jake Noble

Lurene Tuttle as Anna Noble

James Mantell as Ricky Knight

David Hooks as Richard Knight

Frank Birney as Reporter Birney

Rick DiAngelo as Guide #1

Eugene Robert Glazer as Guide #2 (as Gene Glazer)

Tim Donnelly as Richard (as Timothy Donnelly)

Chuck Hayward as Walker Man