- Martin Landau
- Â Commander John Koenig 48 episodes, 1975-1977
- Barbara Bain
- Â Dr. Helena Russell 48 episodes, 1975-1977
- Nick Tate
- Â Alan Carter 42 episodes, 1975-1977
- Zienia Merton
- Â Sandra Benes 35 episodes, 1975-1977
- Sarah Bullen
- Â Main Mission Operative Kate Bullen 1 episode, 1975-1977
- Barry Morse
- Â Professor Victor Bergman 24 episodes, 1975-1976
- Catherine Schell
- Â Maya / ... 25 episodes, 1975-1977
- Prentis Hancock
- Â Paul Morrow 23 episodes, 1975-1976
- Clifton Jones
- Â David Kano 23 episodes, 1975-1976
- Anton Phillips
- Â Dr. Bob Mathias 23 episodes, 1975-1976
- Tony Anholt
- Â Tony Verdeschi 23 episodes, 1976-1977
- John Hug
- Â Bill Fraser 9 episodes, 1976-1977
- Yasuko Nagazumi
- Â Yasko 8 episodes, 1976-1977
- Jeffery Kissoon
- Â Dr. Ben Vincent 7 episodes, 1976-1977
- Albin Pahernik
- Â Creature / ... 6 episodes, 1976-1977
- Annie Lambert
- Â Main Mission Operative Julie Tracy 2 episodes, 1975-1976
- Shane Rimmer
- Â Eagle Pilot / ... 1 episode, 1975-1976
- Robert Rietty
- Â Luke Ferro / ... 1 episode, 1975-1976
- Stuart Damon
- Â Guido Verdeschi / ... 3 episodes, 1975-1977
- Sam Dastor
- Â Dr. Ed Spencer 3 episodes, 1977
- Alibe Parsons
- Â Alibe 3 episodes, 1977
- Peter Porteous
- Â Petrov 2 episodes, 1976
- David Jackson
- Â Alien Voice / ... 1 episode, 1976-1977
- Laraine Humphrys
- Â Information Girl / ... 1 episode, 1975-1976
- Jack Klaff
- Â Guard / ... 1 episode, 1976-1977
- Roy Dotrice
- Â Commissioner Gerald Simmonds 2 episodes, 1975
- Brian Blessed
- Â Dr. Cabot Rowland / ... 2 episodes, 1975-1976
- Isla Blair
- Â Carla / ... 2 episodes, 1975-1976
- Roy Marsden
- Â Alien Invisible / ... 2 episodes, 1976-1977
- Toby Robins
- Â Diana Morris 2 episodes, 1977
- Jeremy Young
- Â Jack Bartlett 2 episodes, 1977
- Laurence Harrington
- Â Jackson / ... 2 episodes, 1976-1977
- Drewe Henley
- Â Joe Ehrlich 2 episodes, 1977
- John Judd
- Â 2nd Security Guard 2 episodes, 1976-1977
- Patrick Westwood
- Â Dr. Shaw 2 episodes, 1977
- Cher Cameron
- Â Louisa 2 episodes, 1977
- Al Lampert
- Â Ken Burdett 2 episodes, 1977
- Billy J. Mitchell
- Â Professor Hunter 2 episodes, 1977
- Earl Robinson
- Â Sandstrom 2 episodes, 1977
- Robert Sheedy
- Â Henry 2 episodes, 1977
- Nicholas Young
- Â Peter Rockwell 2 episodes, 1977
- Marc Zuber
- Â Main Mission Operative / ... 1 episode, 1975-1976
- James Snell
- Â Cousteau / ... 1 episode, 1976-1977
- Ian McShane
- Â Anton Zoref 1 episode, 1975
- Joan Collins
- Â Kara 1 episode, 1975
- Julian Glover
- Â Jarak 1 episode, 1975
- Judy Geeson
- Â Regina Kesslann 1 episode, 1975
- Richard Johnson
- Â Lee Russell 1 episode, 1975
- Leo McKern
- Â Companion Gwent 1 episode, 1976
- Jeremy Kemp
- Â Dr. Ernst Linden 1 episode, 1975
- Margaret Leighton
- Â Arra 1 episode, 1975
- Peter Bowles
- Â Balor 1 episode, 1975
- Anthony Valentine
- Â Male Alien 1 episode, 1975
- Gianni Garko
- Â Tony Cellini 1 episode, 1975
- Orso Maria Guerrini
- Â Luke Ferro 1 episode, 1975
- Paul Jones
- Â Mike Ryan 1 episode, 1975
- Joanna Dunham
- Â Vana 1 episode, 1976
- Caroline Mortimer
- Â Dione 1 episode, 1976
- Giancarlo Prete
- Â Dan Mateo 1 episode, 1976
- Christopher Lee
- Â Captain Zantor 1 episode, 1975
- John Shrapnel
- Â Capt. Jack Tanner 1 episode, 1975
- Lisa Harrow
- Â Anna Davis 1 episode, 1975
- Douglas Wilmer
- Â Commissioner Dixon 1 episode, 1975
- Cyd Hayman
- Â Sue Crawford 1 episode, 1975
- Gay Hamilton
- Â Eva Zoref 1 episode, 1975
- Barry Stokes
- Â Jim Haines 1 episode, 1975
- Dennis Burgess
- Â Neman 1 episode, 1975
- Peter Cushing
- Â Raan 1 episode, 1976
- Lynne Frederick
- Â Shermeen Williams 1 episode, 1976
- Bernard Cribbins
- Â Captain Michael 1 episode, 1976
- Hilary Heath
- Â Laura Adams 1 episode, 1976
- Willoughby Goddard
- Â Taybor 1 episode, 1976
- Carla Romanelli
- Â Melita Kelly 1 episode, 1976
- Ina Skriver
- Â A 1 episode, 1976
- Hildegard Neil
- Â Elizia 1 episode, 1977
- Aubrey Morris
- Â Petros High Priest 1 episode, 1975
- Sarah Douglas
- Â B 1 episode, 1976
- Stuart Wilson
- Â Vindrus 1 episode, 1976
- Freddie Jones
- Â Dr. Charles Logan 1 episode, 1976
- John Standing
- Â Pasc 1 episode, 1976
- James Laurenson
- Â Patrick Osgood 1 episode, 1976
- Patrick Mower
- Â Dave Reilly 1 episode, 1976
- Anthony Nicholls
- Â Dr. James Warren 1 episode, 1976
- Guy Rolfe
- Â Magus 1 episode, 1976
- Godfrey James
- Â Alien Transporter 1 episode, 1976
- Patrick Troughton
- Â Archon 1 episode, 1977
- Nadim Sawalha
- Â Zoran 1 episode, 1977
- Lee Montague
- Â Dorzak 1 episode, 1977
- Pamela Stephenson
- Â Michelle Osgood 1 episode, 1976
- David Prowse
- Â Cloud Creature 1 episode, 1976
- Billie Whitelaw
- Â Zamara 1 episode, 1976
- Bernard Kay
- Â Humanoid 1 episode, 1976
- Deborah Fallender
- Â Carolyn Powell 1 episode, 1976
- Peter Duncan
- Â Cantar 1 episode, 1976
- Michael Gallagher
- Â Etrec 1 episode, 1976
- Karl Held
- Â Jerry Travis 1 episode, 1977
- Ann Firbank
- Â Consul Varda 1 episode, 1977
- Ken Hutchison
- Â Greg Sanderson 1 episode, 1977
- Jill Townsend
- Â Sahala 1 episode, 1977
- Dora Reisser
- Â Interrogator 1 episode, 1977
- Gary Waldhorn
- Â Winters 1 episode, 1976
- Nicholas Campbell
- Â Eddie Collins 1 episode, 1976
- Leigh Lawson
- Â Zarl 1 episode, 1976
- Anouska Hempel
- Â Annette Fraser 1 episode, 1976
- Jess Conrad
- Â Mark Sanders 1 episode, 1976
- Stacy Dorning
- Â Zova 1 episode, 1976
- Michael Sharvell-Martin
- Â Brian / ... 1 episode, 1976
- Veronica Lang
- Â Lyra / ... 1 episode, 1976
- Martha Nairn
- Â Female Operative 1 episode, 1976
- Cassandra Harris
- Â Controller / ... 1 episode, 1977
- Kathryn Leigh Scott
- Â Yesta 1 episode, 1977
- Carolyn Seymour
- Â Eva Lewis 1 episode, 1977
- Gerry Sundquist
- Â Malic 1 episode, 1977
- Philip Madoc
- Â Commander Anton Gorski 1 episode, 1975
- Oliver Cotton
- Â Spearman 1 episode, 1975
- Geoffrey Bayldon
- Â Number Eight 1 episode, 1976
- Maxine Audley
- Â Theia 1 episode, 1976
- Tony Osoba
- Â 1st Security Guard 1 episode, 1976
- Lloyd McGuire
- Â First Engineer 1 episode, 1976
- Max Faulkner
- Â Ted Clifford 1 episode, 1976
- John Alkin
- Â Johnson 1 episode, 1976
- Margaret Inglis
- Â Mirella 1 episode, 1976
- Brian Osborne
- Â Chris Potter 1 episode, 1976
- Anthony Stamboulieh
- Â George Crato 1 episode, 1976
- David Sebastian Bach
- Â Guardian's Brother 1 episode, 1976
- Angus MacInnes
- Â Jelto 1 episode, 1977
- Nigel Pegram
- Â Cernik 1 episode, 1977
- Michael Culver
- Â Pete Irving 1 episode, 1975
- James Smillie
- Â Baxter 1 episode, 1975
- Lon Satton
- Â Benjamin Ouma 1 episode, 1975
- Jon Laurimore
- Â Smitty 1 episode, 1975
- Kevin Stoney
- Â Talos 1 episode, 1976
- Rita Webb
- Â Slatternly Woman 1 episode, 1976
- Brendan Price
- Â Security Guard 1 episode, 1976
- James Leith
- Â Guard 1 episode, 1976
- Gerard Paquis
- Â Lew Picard 1 episode, 1976
- Roger Bizley
- Â MacDonald 1 episode, 1976
- Barbara Wise
- Â Beautiful Girl 1 episode, 1976
- Michael Walker
- Â Carl Renton 1 episode, 1976
- Anthony Blackett
- Â Stal 1 episode, 1976
- Seretta Wilson
- Â Clea 1 episode, 1977
- Arthur White
- Â Kinano 1 episode, 1977
- Hal Galili
- Â Voice 1 episode, 1977
- Barbara Kellerman
- Â Dr. Monique Bouchere 1 episode, 1975
- John Hamill
- Â Mark Dominix 1 episode, 1975
- Eric Carte
- Â Collins 1 episode, 1975
- Alex Scott
- Â Aarchon 1 episode, 1975
- Mary Miller
- Â Freda 1 episode, 1975
- Paul Antrim
- Â Bill Lowry 1 episode, 1975
- Wayne Brooks
- Â Jackie 1 episode, 1975
- Trevor Thomas
- Â Refuel Eagle Pilot 1 episode, 1976
- Anthony Forrest
- Â Carson 1 episode, 1976
- Carolyn Courage
- Â First Girl 1 episode, 1976
- Alan Hunter
- Â Co-Pilot 1 episode, 1976
- Derek Anders
- Â Wayland 1 episode, 1976
- Gregory de Polnay
- Â Peter Garforth 1 episode, 1976
- Peggy Ledger
- Â Old Lady 1 episode, 1976
- Mel Taylor
- Â Andrews 1 episode, 1976
- Richard LeParmentier
- Â Ed Malcolm 1 episode, 1977
- Gyearbuor Asante
- Â Guard 1 episode, 1977
- Kevin Sheehan
- Â 1st Dorcon Operative 1 episode, 1977
- Michael Dickinson
- Â Blake Maine 1 episode, 1977
- Michael Sheard
- Â Dr. Darwin King 1 episode, 1975
- Robert Russell
- Â Hadin 1 episode, 1975
- Eva Reuber-Staier
- Â Jane 1 episode, 1975
- Lawrence Trimble
- Â Steve Abrams 1 episode, 1975
- Nick Brimble
- Â Ray Torens 1 episode, 1976
- Nova Llewellyn
- Â 1st Alphan Woman 1 episode, 1976
- Lydia Lisle
- Â Sally Martin 1 episode, 1976
- Norwich Duff
- Â 1st Operative Texas 1 episode, 1976
- Andrew Lodge
- Â Grasshopper (Captain Duro) / ... 1 episode, 1976
- Raul Newey
- Â Dr. Raul Nunez 1 episode, 1976
- Michael Halsey
- Â 1st Dorcon Soldier 1 episode, 1977
- Walter McMonagle
- Â Les Johnson 1 episode, 1977
- Susan Jameson
- Â Professor Juliet Mackie 1 episode, 1975
- Gerald Staddon
- Â Male Mute 1 episode, 1975
- Lucinda Curtis
- Â Tessa 1 episode, 1976
- Peggy Paige
- Â The Old Crone 1 episode, 1976
- Roy Boyd
- Â Joe Lustig 1 episode, 1977
- Paul Jerricho
- Â 1st Security Guard 1 episode, 1977
- Hamish Patrick
- Â Command Center Alphan 1 episode, 1977
- Jackie Horton
- Â Female Mute 1 episode, 1975
- Dallas Adams
- Â Sam 1 episode, 1976
- Hazel McBride
- Â Female Medical Officer 1 episode, 1977
- Lizy Scott
- Â Outdoor Alphan 1 episode, 1976
- Quentin Pierre
- Â Security Guard / ... (uncredited) 32 episodes, 1975-1977
- Andy Dempsey
- Â Main Mission Operative (uncredited) 23 episodes, 1975-1976
- Suzanne Roquette
- Â Tanya Aleksandr / ... (uncredited) 22 episodes, 1975-1976
- Tony Allyn
- Â Security Guard Tony Allan (uncredited) 20 episodes, 1975-1976
- Loftus Burton
- Â Main Mission Operative Lee Oswald (uncredited) 18 episodes, 1975-1976
- Jenny Cresswell
- Â Operative / ... (uncredited) 17 episodes, 1975-1977
- Alan Harris
- Â Main Mission Operative / ... (uncredited) 16 episodes, 1975-1977
- Michael Stevens
- Â Main Mission Operative (uncredited) 16 episodes, 1975-1976
- Robert Reeves
- Â Peter Reeves (uncredited) 15 episodes, 1976-1977
- Glenda Allen
- Â Operative / ... (uncredited) 14 episodes, 1975-1977
- Joe Dunne
- Â Security Guard / ... (uncredited) 11 episodes, 1975-1977
- Barbara Kelly
- Â Computer Voice / ... (uncredited) 9 episodes, 1975-1976
- Pam Rose
- Â Command Center Operative / ... (uncredited) 8 episodes, 1976
- Maxwell Craig
- Â Security Guard / ... (uncredited) 7 episodes, 1975-1977
- Harry Fielder
- Â Medic / ... (uncredited) 7 episodes, 1976-1977
- Chris Williams
- Â Medic / ... (uncredited) 6 episodes, 1975-1976
- Robert Phillips
- Â Main Mission Operative (uncredited) 6 episodes, 1975-1976
- Raymond Harris
- Â Main Mission Operative (uncredited) 6 episodes, 1975-1976
- Roy Everson
- Â Les Johnston / ... (uncredited) 5 episodes, 1975-1977
- Emily Bolton
- Â Operative June (uncredited) 5 episodes, 1975-1976
- Alf Joint
- Â Security Guard / ... (uncredited) 5 episodes, 1975-1976
- Chai Lee
- Â Main Mission Operative Anna Wong / ... (uncredited) 5 episodes, 1975-1976
- James Fagan
- Â Ken Johnson / ... (uncredited) 5 episodes, 1975-1976
- Paul Weston
- Â Main Mission Operative Lew / ... (uncredited) 4 episodes, 1975-1977
- Robert Atiko
- Â Technician (uncredited) 4 episodes, 1975-1976
- Ann Maj-Brit
- Â Main Mission Operative / ... (uncredited) 4 episodes, 1975-1976
- Binu Balani
- Â Main Mission Operative / ... (uncredited) 4 episodes, 1975-1976
- Judith Hepburn
- Â Nurse (uncredited) 4 episodes, 1975-1976
- Vincent Wong
- Â Medic / ... (uncredited) 4 episodes, 1975
- Peter Brayham
- Â Security Guard / ... (uncredited) 4 episodes, 1976-1977
- Terry Walsh
- Â Clan Guard / ... (uncredited) 4 episodes, 1976-1977
- Roy Scammell
- Â Space Animal / ... (uncredited) 3 episodes, 1975-1977
- Jack McKenzie
- Â Technician / ... (uncredited) 3 episodes, 1975-1976
- Melita Clarke
- Â Main Technician / ... (uncredited) 3 episodes, 1975-1976
- Jan Rennison
- Â Main Mission Operative / ... (uncredited) 3 episodes, 1975-1976
- Laurie Davis
- Â Main Mission Operative / ... (uncredited) 3 episodes, 1975-1976
- Maureen Tan
- Â Main Mission Operative / ... (uncredited) 3 episodes, 1975-1976
- John Lee Barber
- Â Eagle Pilot / ... (uncredited) 3 episodes, 1975-1976
- Vic Armstrong
- Â Main Mission Operative / ... (uncredited) 2 episodes, 1975-1976
- Maggie Henderson
- Â Alphan Medic / ... (uncredited) 2 episodes, 1975-1976
- Anita West
- Â Technician (uncredited) 2 episodes, 1975-1976
- Joy Harrison
- Â Main Mission Operative (uncredited) 2 episodes, 1975-1976
- Eddie Stacey
- Â Clansman / ... (uncredited) 2 episodes, 1975-1976
- Linda Hooks
- Â Alien Girl / ... (uncredited) 2 episodes, 1975-1976
- Lynda Westover
- Â Alphan / ... (uncredited) 2 episodes, 1975-1976
- Eddy Nedari
- Â Technician / ... (uncredited) 2 episodes, 1975-1976
- Lea Brodie
- Â Hilary Preston / ... (uncredited) 2 episodes, 1975
- Christopher Matthews
- Â Main Mission Operative (uncredited) 2 episodes, 1975
- Colin Skeaping
- Â Astronaut Ellis / ... (uncredited) 2 episodes, 1975
- John Clifford
- Â An astronaut / ... (uncredited) 2 episodes, 1975
- Kathleen Mallory
- Â Nurse (uncredited) 2 episodes, 1975
- Lesley Stamps
- Â Main Mission Operative (uncredited) 2 episodes, 1975
- Felicity York
- Â Alphan in corridor #2 / ... (uncredited) 2 episodes, 1976-1977
- Diana Reeves
- Â Nurse / ... (uncredited) 2 episodes, 1976
- Micky Clarke
- Â Number / ... (uncredited) 2 episodes, 1976
- Del Baker
- Â Dorcon Soldier / ... (uncredited) 2 episodes, 1977
- Louise Jameson
- Â Survivor (uncredited) 1 episode, 1975
- Valerie Leon
- Â Thule Girl (uncredited) 1 episode, 1975
- David Robb
- Â Main Mission Operative (uncredited) 1 episode, 1975
- Gwen Taylor
- Â Nurse (uncredited) 1 episode, 1975
- Rula Lenska
- Â Joan Conway (uncredited) 1 episode, 1975
- Gareth Hunt
- Â Eagle Pilot (uncredited) 1 episode, 1975
- Richard Eden
- Â Technicican (uncredited) 1 episode, 1975
- Don Fellows
- Â GTV Newscaster (uncredited) 1 episode, 1975
- Jan Harvey
- Â Alpha News Service Girl (uncredited) 1 episode, 1975
- Sandor Elès
- Â Eagle Technician (uncredited) 1 episode, 1975
- Norma West
- Â Main Mission Operative (uncredited) 1 episode, 1975
- Bob Sherman
- Â Newscaster (uncredited) 1 episode, 1975
- Terence Plummer
- Â Survivor (uncredited) 1 episode, 1975
- Rhonda Parker
- Â Kaldorian (uncredited) 1 episode, 1975
- Valerie Van Ost
- Â Main Mission Operative (uncredited) 1 episode, 1975
- Steve Emerson
- Â Depot Security (uncredited) 1 episode, 1975
- Suzette St. Clair
- Â Thulian (uncredited) 1 episode, 1975
- David Ellison
- Â Ted (uncredited) 1 episode, 1975
- Ron Tarr
- Â Survivor (uncredited) 1 episode, 1975
- Martin Grace
- Â Security Guard (uncredited) 1 episode, 1975
- Adrienne Burgess
- Â Revered One (uncredited) 1 episode, 1975
- Gerry Crampton
- Â Aggressive Main Mission Operative (uncredited) 1 episode, 1975
- Ian Ruskin
- Â Revered One (uncredited) 1 episode, 1975
- Carolyn Hudson
- Â Thulian (uncredited) 1 episode, 1975
- Milos Kirek
- Â Young (Technical) (uncredited) 1 episode, 1975
- Jack Shephard
- Â Thulian (uncredited) 1 episode, 1975
- Angela Staines
- Â Kaldorian (uncredited) 1 episode, 1975
- John Gleeson
- Â Voice of Davis (uncredited) 1 episode, 1975
- Christine Donna
- Â Main Mission Operative (uncredited) 1 episode, 1975
- Corinne Skinner-Carter
- Â Prof. Angela Robinson (uncredited) 1 episode, 1975
- Colin Rix
- Â Eagle One Co-Pilot (uncredited) 1 episode, 1975
- Alan Meacham
- Â Sandos (uncredited) 1 episode, 1975
- Nik Zaran
- Â Astronaut Jackson (uncredited) 1 episode, 1975
- Christine Hewett
- Â Kaldorian (uncredited) 1 episode, 1975
- Jeremy Anthony
- Â Main Mission Operative (uncredited) 1 episode, 1975
- Barbara Bermel
- Â Thulian (uncredited) 1 episode, 1975
- Lew Hooper
- Â Medic (uncredited) 1 episode, 1975
- Claire McLellan
- Â Morrow's Daughter (uncredited) 1 episode, 1975
- Jenny Devenish
- Â Thulian (uncredited) 1 episode, 1975
- Paul Kirby
- Â Medic (uncredited) 1 episode, 1975
- John Oxley
- Â Bannion (uncredited) 1 episode, 1975
- Margaret Lawley
- Â Revered One (uncredited) 1 episode, 1975
- Juliet King
- Â Nurse (uncredited) 1 episode, 1975
- Robert Driscoll
- Â Revered One (uncredited) 1 episode, 1975
- Ronald Chenery
- Â Flight Engineer George Osgood (uncredited) 1 episode, 1975
- Michael Boothe
- Â Darian in spacesuit (uncredited) 1 episode, 1975
- Robin Scott
- Â Eric Sparkman (uncredited) 1 episode, 1975
- Paul Kirby
- Â Medic (uncredited) 1 episode, 1975
- Ellen Sheean
- Â Revered One (uncredited) 1 episode, 1975
- Trevor Ainsley
- Â Technician (uncredited) 1 episode, 1975
- Michael Zorba
- Â Operative Michael (uncredited) 1 episode, 1975
- Guy Groen
- Â Technician (Eagle box stacking) (uncredited) 1 episode, 1975
- Kathy Mallory
- Â Nurse (uncredited) 1 episode, 1975
- Alan Roberto
- Â Morrow's Son (uncredited) 1 episode, 1975
- Saad Ghazi
- Â Medic (uncredited) 1 episode, 1975
- David Rhys Anderson
- Â Frank Warren (uncredited) 1 episode, 1975
- Fran Miller
- Â Nurse in Corridor (uncredited) 1 episode, 1975
- Janice Hills
- Â Alphan in Corridor (uncredited) 1 episode, 1975
- Dave Murphy
- Â Thulian (uncredited) 1 episode, 1975
- Laurie Davis
- Â Stewardess 2 (uncredited) 1 episode, 1975
- Philip Clifton
- Â Technician (uncredited) 1 episode, 1975
- Terry Pendle
- Â Revered One (uncredited) 1 episode, 1975
- Vicki Michelle
- Â Barbara (uncredited) 1 episode, 1976
- Terry Richards
- Â That's (uncredited) 1 episode, 1976
- Neil McCaul
- Â Alien in cave (uncredited) 1 episode, 1976
- Roy Stewart
- Â Tall Alien in Cave (uncredited) 1 episode, 1976
- George Lane Cooper
- Â Overseer (uncredited) 1 episode, 1976
- Nick Hobbs
- Â Medical Security Guard (uncredited) 2 episodes, 1976-1977
- Doug Robinson
- Â Clansman (uncredited) 1 episode, 1976
- Dinny Powell
- Â Psychon (uncredited) 1 episode, 1976
- Frank Maher
- Â Decontamination Operative (uncredited) 1 episode, 1976
- Bill Westley
- Â Security Guard (uncredited) 1 episode, 1976
- Saul Reichlin
- Â Second Mining Engineer (uncredited) 1 episode, 1976
- Romo Gorrara
- Â Running Technician (uncredited) 1 episode, 1976
- Valentino Musetti
- Â Spirit Mateo (uncredited) 1 episode, 1976
- Jenny Clare
- Â Alphan Girl (uncredited) 1 episode, 1976
- Terry Yorke
- Â Ape Man (uncredited) 1 episode, 1976
- Jürgen Andersen
- Â Vegan (uncredited) 1 episode, 1976
- Tim Condren
- Â Clansman (uncredited) 1 episode, 1976
- Zena Clifton
- Â Vegan (uncredited) 1 episode, 1976
- Big Jim Sullivan
- Â Musician (uncredited) 1 episode, 1976
- John Ketteringham
- Â Command Center Operative (uncredited) 1 episode, 1976
- Reuben Martin
- Â Gorilla (uncredited) 1 episode, 1976
- Claire Lutter
- Â Main Mission Operative (uncredited) 1 episode, 1976
- John Dixon
- Â Alien in cave (uncredited) 1 episode, 1976
- Suzanne Heimer
- Â Nurse (uncredited) 1 episode, 1976
- Carol Dee
- Â Patient (uncredited) 1 episode, 1976
- Vernon Morris
- Â Male Botanist (uncredited) 1 episode, 1976
- Xanthi Gardner
- Â Female Botanist (uncredited) 1 episode, 1976
- Geoffrey Moon
- Â Short alien in cave (uncredited) 1 episode, 1976
- Richard Adams
- Â Technician (uncredited) 1 episode, 1976
- Jacqueline Delhaye
- Â Main Mission Operative (uncredited) 1 episode, 1976
- Charlie Price
- Â Guard (uncredited) 1 episode, 1976
- Robert Case
- Â Security Guard (uncredited) 1 episode, 1976
- Erica Svenson
- Â Nurse (uncredited) 1 episode, 1976
- David Clare
- Â Command Center Operative (uncredited) 1 episode, 1976
- Barry Rohde
- Â Vegan (uncredited) 1 episode, 1976
- Robert Reeves
- Â Pilot (Corridor) (uncredited) 1 episode, 1976
- Mike Sirett
- Â Technician (uncredited) 1 episode, 1976
- Richard Shore
- Â Technician (uncredited) 1 episode, 1976
- Andy Sutcliffe
- Â Main Mission Operative (uncredited) 1 episode, 1976
- Andy Cummings
- Â Operative (uncredited) 1 episode, 1976
- Nina Mitchen
- Â Alphan (uncredited) 1 episode, 1976
- Rikki Howard
- Â Guard (uncredited) 1 episode, 1977
- Katya Wyeth
- Â Guard (uncredited) 1 episode, 1977
- Vida Taylor
- Â Guard (uncredited) 1 episode, 1977
- Marc Smith
- Â Alien Computer (uncredited) 1 episode, 1977
- Frank Henson
- Â Security Guard (uncredited) 1 episode, 1977
- Geoffrey Greenhill
- Â Phirly (uncredited) 1 episode, 1977
- Beulah Hughes
- Â Guard (uncredited) 1 episode, 1977
- Claire Russell
- Â Model (uncredited) 1 episode, 1977
- Les White
- Â Dorcon Soldier (uncredited) 1 episode, 1977
- Chris Diggins
- Â Alphan (uncredited) 1 episode, 1977