Guy Williams as Dr. John Robinson
June Lockhart as Maureen Robinson
Mark Goddard as Major Don West
Marta Kristen as Judy Robinson
Bill Mumy as Will Robinson
Angela Cartwright as Penny Robinson
Jonathan Harris as Dr. Zachary Smith
Dawson Palmer as Monster
Jim Mills as Saticon #1
Harry Monty as Geoo
Dee Hartford as Verda
Fritz Feld as Mr. Zumdish
Sheila Allen as Aunt Gamma
Ron Gans as Alien Leader
Ronald Weber as Alien Dictator
Albert Salmi as Alonzo P. Tucker
Vitina Marcus as Athena
Michael Rennie as The Keeper
Leonard Stone as Farnum
Robert Foulk as Cragmire
Marcel Hillaire as Junkman
Don Matheson as IDAK Alpha 12
Tiger Joe Marsh as Elevator Operator
Keith Taylor as Edgar
Allan Melvin as Enforcer Claudio
Hoke Howell as Security Guard
Larry Dean as Mummy
Warren Oates as Jimmy Hapgood
Reta Shaw as Aunt Clara Simms
Werner Klemperer as Bolix
Michael Ansara as The Ruler
Strother Martin as Nerim
Mercedes McCambridge as Sybilla
Royal Dano as Major Domo
Michael J. Pollard as The Boy
Henry Jones as Jeremiah Smith
Gerald Mohr as Morbus
Mike Kellin as Myko
James Westerfield as Dr. Marvello
Malachi Throne as Thief
Torin Thatcher as The Space Trader
Dennis Patrick as Keema
Wally Cox as Tiabo
John Abbott as Sesmar
Liam Sullivan as Nexus
John Carradine as Arcon
Daniel J. Travanti as Space Hippie
Al Lewis as Zalto
Hans Conried as Sagramonte
Francine York as Niolani
Music by the great Kevin MacLeod