- Peter Tuddenham - Zen / ORAC
- Peter Tuddenham - Zen
- Peter Tuddenham - Slave / ORAC
- Gareth Thomas - Roj Blake
- Steven Pacey - Del Tarrant
- Jan Chappell - Cally
- Jan Chappell - Cally (voice) (uncredited)
- Glynis Barber - Soolin
- Glynis Barber - Mutoid
- Brian Croucher - Travis
- Brian Croucher - Space Commander Travis
- Morris Barry - Dr. Wiler
- Suzan Farmer - Meegat
- David Sterne - Guard
- Juliet Hammond-Hill - Pella
- Peter Byrne - Justin
- Richard Hurndall - Nebrox
- Michael Gough - Hower
- Darien Angadi - Ro
- John Abineri - Ushton
- Ian Cullen - Base Commander Escon
- Richard Bebb - Ven Glynd
- Derek Farr - Ensor
- Bobbie Brown - Zeeona
- T. P. McKenna - Sarkoff
- Ian Barritt - Ultra 3
- Vernon Dobtcheff - The Chairman
- Stratford Johns - Belkov
- Sabina Franklyn - Chesil
- Leslie Schofield - Sub-Commander Raiker
- Michael Troughton - Pilot Four-Zero
- Harriet Philpin - Alta Two
- David Quilter - The Tracer
- Beth Morris - Sara
- Lynda Bellingham - Vena
- Candace Glendenning - Rashel
- Cy Grant - Hal Mellanby
- Paul Shelley - Major Provine
- David Haig - Forres
- Damien Thomas - Atlan
- Roy Kinnear - Keller
- John Hollis - Lom
- Geoffrey Burridge - Dorian
- Richard Beale - Saymon
- Carol Hawkins - Kerril
- Julian Glover - Professor Kayn
- Isla Blair - Sinofar
- Aubrey Woods - Krantor
- Bruce Purchase - Gola
- Paul Daneman - Dr. Bellfriar
- Carol Royle - Mutoid
- William Squire - Kommissar
- Kevin Lloyd - Trooper Par
- Valentine Dyall - Nori
- Stephen Yardley - Investigator Reeve
- Karl Howman - Bek
- Roy Boyd - Zukan
- Alan Lake - Chel
- Kathleen Byron - Clonemaster Fen
- Betty Marsden - Verlis
- John Westbrook - Muller
- Tom Chadbon - Del Grant
- Dicken Ashworth - Gunn-Sar
- Brian Capron - Rafford
- Malcolm Stoddard - Leitz
- Marc Zuber - Tarvin
- Yolande Palfrey - Veron
- Jacqueline Pearce - Servalan
- Arthur Hewlett - Old Man
- Glyn Owen - Commander Leylan
- Stephen Greif - Space Commander Travis
- Alison Glennie - Kate
- Ronald Leigh-Hunt - C.A. One
- Patsy Smart - Giroc
- Sylvia Coleridge - Croupier
- Primi Townsend - Zee
- Rosalind Bailey - Gambit (voice)
- Michael Melia - Federation Trooper
- Colin Baker - Bayban
- Souad Faress - Selma
- Ronald Lacey - Tynus
- Tony Caunter - Ensor Jr.
- Christopher Neame - Colonel Quute
- John Bennett - Coser
- Caroline Holdaway - Piri
- Andrew Robertson - Space Commander
- Gillian McCutcheon - Kostos
- David Neal - Gerren
- Judy Buxton - Inga
- Pamela Salem - Kara
- Jack McKenzie - Patar
- Robert Morris - Major Hunda
- Astley Jones - Eldon
- Ric Young - Ginka
- David Ryall - Selman
- Brian Blessed - Vargas
- Robert Russell - Laran
- Robert Beatty - Bran Foster
- Robert James - Ven Glynd
- Jeremy Wilkin - Dev Tarrant
- Pippa Steel - Maja Veron
- Gillian Bailey - Ravella
- Margaret John - Arbiter
- Susan Field - Alta Morag
- Brett Forrest - Krell
- Norman Tipton - Navigator Idas
- Norman Tipton - Navigator Artix
- Tom Kelly - Nova
- Michael MacKenzie - Dainer
- Peter Childs - Arco
- Bill Weston - Garton
- Tony Smart - 1st Alien
- Frank Henson - Alien
- Ania Marson - Geela
- Barry Jackson - Dr. Kendall
- Nigel Humphreys - Sonheim
- Kate Coleridge - Levett
- John Bryans - Senator Bercol
- John Bryans - Shrinker
- Carl Forgione - Grovane
- David Bailie - Chevner
- John Rolfe - Terloc
- Michael Halsey - Tel Varon
- Michael Halsey - Zee
- Ian Thompson - Farren
- Christian Roberts - Dr. Renor
- Carinthia West - Tyce
- Peter Craze - Prell
- Peter Craze - Servalan's Assistant
- James Lister - Space Surgeon Maryatt
- John Savident - Fleet Warden-General Samor
- John Savident - Egrorian
- Sheila Ruskin - Alta One
- Roy Evans - Slave
- Adrienne Burgess - Hanna
- Derek Smith - Largo
- Scott Fredericks - Carnell
- Brian Miller - Assistant Kommissar
- Kevin Stoney - Ardus
- Kevin Stoney - Councillor Joban
- Alan Halley - Arie
- John Leeson - Toise
- John Leeson - Pasco
- Sue Bishop - Mutoid
- Claire Lewis - Zil
- Colin Farrell - Gambrill
- Colin Higgins - Tak
- James Coyle - Molok
- Julia Vidler - Avalon
- Julia Vidler - Barr
- James Kerry - Cauder
- Lindy Alexander - Ralli
- Sidney Kean - Vetnor
- Nigel Gregory - Arrian
- Frieda Knorr - Governor Le Grand
- Denis Carey - Docholli
- Nicolette Roeg - Chenie
- Deep Roy - Moloch (voice)
- Deep Roy - Decima
- Deep Roy - The Klute
- Freda Jackson - Tara
- Shaun Curry - Rod
- John Bown - Durkim
- Gareth Armstrong - Parton
- Jenny Twigge - Lurena
- David Webb - Stot
- Paul Toothill - Marcol
- Michael Maynard - Leeth
- Sally Harrison - Lauren Mellanby
- Richard Franklin - Federation Trooper
- Michael Sheard - Klegg
- Doyne Bird - Harmon
- Helen Blatch - Receptionist
- Malcolm Bullivant - Bershar
- Ben Howard - Mori
- Judy Matheson - Mutoid
- Sam Dastor - The Caliph
- Terry Scully - Groff
- Marcus Powell - The Thaarn
- Andrew Burt - Ven Jarvik
- Frank Gatliff - Dastor
- Anthony Gardner - Captain Shad
- John J. Carney - Sherm
- Beth Harris - C.A. Two
- Donald Douglas - Major Grenlee
- David Gillies - Hob
- Philip Bloomfield - Balon
- Stuart Fell - Dortmunn
- Stuart Fell - Subterron
- Stuart Fell - Goth Warrior
- Lorna Heilbron - Sula
- Stephen Jenn - Ultra 2
- Davyd Harries - Doran
- Debbi Blythe - Poola
- John Hartley - Section Leader Grose
- Mark Sheridan - Unit Commander Lector
- Paul Mark Elliott - Vinni
- Stewart Bevan - Max
- David Sibley - Commentator
- Heather Wright - Reeval
- Richard Clifford - Toron
- Paul Ridley - Cato
- John Quentin - Practor
- Edgar Wreford - Forbus
- Nick Brimble - General
- Neil Dickson - Avandir
- Cyril Appleton - Sgt. Hask
- George Lee - Igin
- Barbara Shelley - Dr. Plaxton
- Peter Sands - Bomber
- Leonard Kavanagh - Napier
- William Lindsay - Captain
- Max Harvey - Borr
- David Boyce - Og
- Douglas Fielding - Technician
- Peter Attard - Benos
- Adam Blackwood - Tok
- Daniel Hill - Chasgo
- Jonathan David - Don Keller
- Antony Brown - Doctor Slaten
- Norman Hartley - Captain Kennedy
- Larry Noble - Pinder
- Dean Harris - Finn
- Rick James - Chalsa
- Charles Augins - Lod
- Simon Merrick - Boorva
- Brian Spink - Mida
- David Collings - Deva
- Sasha Mitchell - Arien
- Janet Lees-Price - Klyn
- Mark Holmes - Guard
- Mark York - Sub-Commander Cheney
- Derrick Branche - Amagon Guard
- Terence Plummer - Scavenger
- Terry Richards - Scavenger
- Les White - Alta Guard
- Terry Yorke - Alta Guard
- Graham Simpson - Officer
- Peter Miles - Secretary Rontane
- Victoria Fairbrother - Major Thania
- Paul Grist - Cevedic
- Harry Jones - Jarriere
- Pat Gorman - Trantinian planet hopper Captain
- Ron Tarr - Patrol Leader
- Paul Weston - Goth Warrior
- Hugh Dickson - Keldon Traffic Controller
- Michael Spice - Nova Queen Pilot (voice)
- Martyn Read - Nagu
- Michael Gaunt - Dr. Bax
- David Hayward - Teague
- Vere Lorrimer
- Dudley Simpson
Deep Roy interpreta a Moloch (voice) en la serie.
Roy Kinnear interpreta a Keller en la serie.
Vernon Dobtcheff hace el papel de The Chairman.
Ronald Lacey interpreta a Tynus en la serie.
Aubrey Woods interpreta a Krantor en la serie.
David Bailie hace el papel de Chevner.
Michael Gough interpreta a Hower en la serie.
Julian Glover interpreta a Professor Kayn en la serie.
Isla Blair interpreta a Sinofar en la serie.
Robert Beatty hace el papel de Bran Foster.
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