- Guy Williams
-  Dr. John Robinson 84 episodes, 1965-1968
                    
- June Lockhart
-  Maureen Robinson 84 episodes, 1965-1968
                    
- Mark Goddard
-  Major Don West 84 episodes, 1965-1968
                    
- Marta Kristen
-  Judy Robinson / ... 84 episodes, 1965-1968
                    
- Bill Mumy
-  Will Robinson 84 episodes, 1965-1968
                    
- Angela Cartwright
-  Penny Robinson / ... 84 episodes, 1965-1968
                    
- Jonathan Harris
-  Dr. Zachary Smith / ... 83 episodes, 1965-1968
                    
- Dawson Palmer
-  Monster / ... 5 episodes, 1965-1967
                    
- Jim Mills
-  Saticon #1 / ... 1 episode, 1966-1968
                    
- Harry Monty
-  Geoo / ... 1 episode, 1966-1968
                    
- Dee Hartford
-  Verda / ... 3 episodes, 1966-1968
                    
- Fritz Feld
-  Mr. Zumdish 3 episodes, 1966-1967
                    
- Sheila Allen
-  Aunt Gamma / ... 3 episodes, 1965-1968
                    
- Ron Gans
-  Alien Leader / ... 2 episodes, 1966-1967
                    
- Ronald Weber
-  Alien Dictator / ... 1 episode, 1966-1968
                    
- Albert Salmi
-  Alonzo P. Tucker / ... 2 episodes, 1966-1967
                    
- Vitina Marcus
-  Athena / ... 2 episodes, 1966-1967
                    
- Michael Rennie
-  The Keeper 2 episodes, 1966
                    
- Leonard Stone
-  Farnum 2 episodes, 1967-1968
                    
- Robert Foulk
-  Cragmire / ... 2 episodes, 1967-1968
                    
- Marcel Hillaire
-  Junkman / ... 2 episodes, 1967-1968
                    
- Don Matheson
-  IDAK Alpha 12 / ... 2 episodes, 1965-1967
                    
- Tiger Joe Marsh
-  Elevator Operator / ... 2 episodes, 1966-1967
                    
- Keith Taylor
-  Edgar / ... 2 episodes, 1965-1968
                    
- Allan Melvin
-  Enforcer Claudio / ... 1 episode, 1966
                    
- Hoke Howell
-  Security Guard / ... 1 episode, 1965-1968
                    
- Larry Dean
-  Mummy / ... 1 episode, 1967
                    
- Warren Oates
-  Jimmy Hapgood 1 episode, 1965
                    
- Reta Shaw
-  Aunt Clara Simms 1 episode, 1965
                    
- Michael J. Pollard
-  The Boy 1 episode, 1966
                    
- Michael Ansara
-  The Ruler 1 episode, 1966
                    
- Royal Dano
-  Major Domo 1 episode, 1966
                    
- Werner Klemperer
-  Bolix 1 episode, 1966
                    
- Strother Martin
-  Nerim 1 episode, 1966
                    
- James Westerfield
-  Dr. Marvello 1 episode, 1966
                    
- Gerald Mohr
-  Morbus 1 episode, 1966
                    
- Liam Sullivan
-  Nexus 1 episode, 1966
                    
- Mercedes McCambridge
-  Sybilla 1 episode, 1966
                    
- Henry Jones
-  Jeremiah Smith 1 episode, 1966
                    
- Wally Cox
-  Tiabo 1 episode, 1966
                    
- Mike Kellin
-  Myko 1 episode, 1966
                    
- Torin Thatcher
-  The Space Trader 1 episode, 1966
                    
- Dennis Patrick
-  Keema 1 episode, 1966
                    
- Malachi Throne
-  Thief 1 episode, 1966
                    
- John Abbott
-  Sesmar 1 episode, 1966
                    
- John Carradine
-  Arcon 1 episode, 1967
                    
- Francine York
-  Niolani 1 episode, 1967
                    
- Hans Conried
-  Sagramonte 1 episode, 1967
                    
- Daniel J. Travanti
-  Space Hippie 1 episode, 1967
                    
- Al Lewis
-  Zalto 1 episode, 1967
                    
- Walter Burke
-  Mr. O. M. 1 episode, 1967
                    
- Woodrow Parfrey
-  Colonel Silas Fogey 1 episode, 1967
                    
- Alan Hewitt
-  Lemnoc 1 episode, 1967
                    
- Vincent Beck
-  Megazor 1 episode, 1967
                    
- Sean McClory
-  Hamish 1 episode, 1967
                    
- Arthur Batanides
-  Rangah 1 episode, 1967
                    
- Ronald Long
-  Admiral Zahrk 1 episode, 1967
                    
- Lew Gallo
-  Commander Fletcher 1 episode, 1967
                    
- Tommy Farrell
-  Cyborg 1 episode, 1967
                    
- Grant Sullivan
-  Alien #764 1 episode, 1967
                    
- Alberto Monte
-  Chavo 1 episode, 1967
                    
- John Crawford
-  Dr. Chronos 1 episode, 1968
                    
- Michael Conrad
-  Creech 1 episode, 1968
                    
- Stanley Adams
-  Tybo 1 episode, 1968
                    
- Abraham Sofaer
-  Sobram 1 episode, 1968
                    
- Gil Rogers
-  Bartholomew 1 episode, 1968
                    
- Jim Gosa
-  Gilt Proto 1 episode, 1968
                    
- Walter Sande
-  Sheriff George Baxendale 1 episode, 1965
                    
- Françoise Bush
-  Moela 1 episode, 1965
                    
- Kurt Russell
-  Quano 1 episode, 1966
                    
- Kym Karath
-  Princess 1 episode, 1966
                    
- Sherry Jackson
-  Effra 1 episode, 1966
                    
- Ted Cassidy
-  Slave 1 episode, 1966
                    
- Kevin Hagen
-  Alien 1 episode, 1966
                    
- Peter Brocco
-  Alien Leader 1 episode, 1966
                    
- Melinda O. Fee
-  Fenestra 1 episode, 1966
                    
- Larry Ward
-  Ohan 1 episode, 1966
                    
- Mickey Manners
-  Dee 1 episode, 1966
                    
- Lyle Waggoner
-  Mechanical Man I 1 episode, 1967
                    
- Linda Gaye Scott
-  Alien Girl 1 episode, 1967
                    
- Lou Wagner
-  J-5 1 episode, 1967
                    
- Corinna Tsopei
-  Princess Reyka 1 episode, 1967
                    
- Jim Boles
-  Smeek 1 episode, 1967
                    
- Pitt Herbert
-  Grover 1 episode, 1967
                    
- Bern Hoffman
-  Thor 1 episode, 1967
                    
- Don Eitner
-  Sergeant Horatio Smith 1 episode, 1967
                    
- Harry Raybould
-  Urso 1 episode, 1967
                    
- Carol Williams
-  Alien #1220 1 episode, 1967
                    
- Richard Krisher
-  MXR 1 episode, 1967
                    
- Arte Johnson
-  Fedor 1 episode, 1968
                    
- James Millhollin
-  Willoughby the Llama 1 episode, 1968
                    
- Charles Horvath
-  Guard #1 1 episode, 1968
                    
- Byron Morrow
-  General Squires 1 episode, 1968
                    
- Tol Avery
-  Warden 1 episode, 1968
                    
- Ken Mayer
-  Pleiades Pete 1 episode, 1966
                    
- Bill Troy
-  Handsome Alien 1 episode, 1966
                    
- Claire Wilcox
-  Stacy 1 episode, 1967
                    
- Gary Tigerman
-  Oggo 1 episode, 1967
                    
- Kenya Coburn
-  Zaybo 1 episode, 1967
                    
- Ralph Lee
-  Mechanical Man II 1 episode, 1967
                    
- Eric Matthews
-  QZW 1 episode, 1967
                    
- Miriam Schiller
-  Miss Teutonium 1 episode, 1968
                    
- Robert Easton
-  Newsman Lacy 1 episode, 1965
                    
- Michael Greene
-  Nubu 1 episode, 1966
                    
- Edy Williams
-  NON 1 episode, 1967
                    
- Norman Leavitt
-  Charlie 1 episode, 1967
                    
- Harry Harvey
-  Grover 1 episode, 1965
                    
- Robert Pine
-  Craig 1 episode, 1967
                    
- Carroll Roebke
-  TAT 1 episode, 1967
                    
- Helen Kleeb
-  Phone Operator Rachel 1 episode, 1965
                    
- Anne Dore
-  First Selectman 1 episode, 1965
                    
- Donald Losby
-  Davey Sims 1 episode, 1965
                    
- Johnny Tuohy
-  First Boy (the tall, thin blonde) 1 episode, 1965
                    
- Dick Tufeld
-  The Robot / ... (uncredited) 84 episodes, 1965-1968
                    
- Bob May
-  The Robot (uncredited) 82 episodes, 1965-1968
                    
- Judy the Chimpanzee
-  Debbie the Bloop (uncredited) 11 episodes, 1965-1967
                    
- John Hunt
-  Saticon #2 / ... (uncredited) 7 episodes, 1966-1968
                    
- Joe E. Tata
-  Computer Eye / ... (uncredited) 5 episodes, 1967
                    
- Paul Kessler
-  Saticon #3 / ... (uncredited) 4 episodes, 1966-1968
                    
- Bart La Rue
-  Alien #2 / ... (uncredited) 4 episodes, 1967-1968
                    
- Fred Krone
-  Alien Monster / ... (uncredited) 4 episodes, 1967-1968
                    
- Jeffrey Trayler
-  Alien Soldier #2 / ... (uncredited) 4 episodes, 1967-1968
                    
- Paul Zastupnevich
-  Bearded Foreign Correspondent / ... (uncredited) 3 episodes, 1965-1967
                    
- Don Forbes
-  TV Commentator (uncredited) 3 episodes, 1965
                    
- Robby the Robot
-  Robotoid / ... (uncredited) 3 episodes, 1966-1967
                    
- Mike Donovan
-  Hades Monster / ... (uncredited) 3 episodes, 1966
                    
- Frank Parker
-  Security Guard (uncredited) 2 episodes, 1965-1968
                    
- William Bramley
-  Mr. Nobody / ... (uncredited) 2 episodes, 1965-1966
                    
- Janos Prohaska
-  Giant Bird Monster / ... (uncredited) 2 episodes, 1965-1966
                    
- Theodore Lehmann
-  Alien / ... (uncredited) 2 episodes, 1965-1966
                    
- Ford Rainey
-  The President (uncredited) 2 episodes, 1965
                    
- Robert 'Big Buck' Maffei
-  The Giant Cyclops (uncredited) 2 episodes, 1965
                    
- Lamar Lundy
-  The Giant / ... (uncredited) 2 episodes, 1965
                    
- Sue England
-  Female Robot / ... (uncredited) 2 episodes, 1966-1967
                    
- Michael Fox
-  Alien on Computer Screen / ... (uncredited) 2 episodes, 1966-1967
                    
- Eldon Hansen
-  Robot Guard / ... (uncredited) 2 episodes, 1966-1967
                    
- Gregory Morton
-  Canto of Quasti / ... (uncredited) 2 episodes, 1966
                    
- Wilbur Evans
-  Lighted Head Leader (uncredited) 2 episodes, 1966
                    
- Ralph Madlener
-  Monster #2 / ... (uncredited) 2 episodes, 1968
                    
- Charles Dierkop
-  Horned Mutant (uncredited) 1 episode, 1965
                    
- Richard Basehart
-  Shakespeare-Reading Tape Recorder Voice (uncredited) 1 episode, 1965
                    
- Fred Crane
-  Alpha Control Technician (uncredited) 1 episode, 1965
                    
- Eddie Rosson
-  Lunon (uncredited) 1 episode, 1965
                    
- Hal Torey
-  General (uncredited) 1 episode, 1965
                    
- Tom Allen
-  Inspector (uncredited) 1 episode, 1965
                    
- Joe Ryan
-  Luminary (uncredited) 1 episode, 1965
                    
- Eddie Quillan
-  Bartender (uncredited) 1 episode, 1966
                    
- Chuck Roberson
-  Alien Fighter (uncredited) 1 episode, 1966
                    
- Lane Bradford
-  Barfly (uncredited) 1 episode, 1966
                    
- Charles Morton
-  Barfy (uncredited) 1 episode, 1966
                    
- Ollie O'Toole
-  Robotoid (uncredited) 1 episode, 1966
                    
- Maxine Gates
-  Fat Princess (uncredited) 1 episode, 1966
                    
- Hal Jon Norman
-  Dog-faced Alien (uncredited) 1 episode, 1966
                    
- Frank Graham
-  Alien (uncredited) 1 episode, 1966
                    
- Eddie Quinlan
-  Bartender (uncredited) 1 episode, 1966
                    
- Charles Arthur
-  Smith's Double (uncredited) 1 episode, 1966
                    
- Harry Varteresian
-  Vicho (uncredited) 1 episode, 1966
                    
- June Foray
-  Gundemar (uncredited) 1 episode, 1967
                    
- Duke Fishman
-  Convict (uncredited) 1 episode, 1967
                    
- Frank Delfino
-  Troll of Niffelheim (uncredited) 1 episode, 1967
                    
- Stephan Merjanian
-  Alien Hippie #4 (uncredited) 1 episode, 1967
                    
- Gil Perkins
-  Convict (uncredited) 1 episode, 1967
                    
- Ben Frommer
-  Convict (uncredited) 1 episode, 1967
                    
- Zamba
-  The Lion (uncredited) 1 episode, 1967
                    
- Lars Hensen
-  Convict (uncredited) 1 episode, 1967
                    
- Craig Duncan
-  Deek (uncredited) 1 episode, 1967
                    
- Craig Chudy
-  Alien Soldier #3 (uncredited) 1 episode, 1967
                    
- Mike Morelli
-  Convict (uncredited) 1 episode, 1967
                    
- Orwin C. Harvey
-  Third Alien Guard (uncredited) 1 episode, 1967
                    
- Joey Russo
-  Young Smith (uncredited) 1 episode, 1967
                    
- Dave Dunlap
-  First Alien Guard (uncredited) 1 episode, 1967
                    
- Jeff County
-  Gundemar (uncredited) 1 episode, 1967
                    
- Erwin Niel
-  Second Alien Guard (uncredited) 1 episode, 1967
                    
- Maritza Elsen
-  Alien Soldier #1 (uncredited) 1 episode, 1967
                    
- Rita Fabotta
-  Alien Soldier #4 (uncredited) 1 episode, 1967
                    
- Seymour Konic
-  Fourth Alien Guard (uncredited) 1 episode, 1967
                    
- Brent Davis
-  Mike Officer (uncredited) 1 episode, 1968
                    
- Thant Brann
-  Officer (uncredited) 1 episode, 1968