With its astronomical conceptual themes, production values, and budget, Space: 1999 demanded a suitably larger-than-life line-up of guest acting talent from the small and big screens to enliven its outlandish alien characters. Some are benevolent, some are antagonistic, but all of them are memorable in their grandiose performances.

Let's count down our favourite guest artists of Space: 1999 who portrayed some of the series' most powerfully distinctive and imposing alien characters!

Year 1

Following Space: 1999's production order (the superior way to experience the series), the first star guest to portray an alien character doesn't materialise until the fifth episode; Earthbound. A sequel to Breakaway that spells out the doomed fate of the utterly unlikable Commissioner Simmonds, Earthbound features the debut of the first humanoid alien race of the series. The peaceful Kaldorians are led by Captain Zantor, portrayed with a looming, quietly graceful performance from the legendary Christopher Lee. His seven-movie portrayal of Count Dracula for Hammer is complimented by a lengthily career across a plethora of other cinematic classics.

Fellow Hammer man and close friend Peter Cushing portrays a more trickster alien in Missing Link, in which the scheming Raan plots to exploit Commander Koenig for his experiments. Cushing's other works across horror and sci-fi included Star Wars, Dr. Who and the Daleks, At the Earth's Core, The Hound of the Baskervilles, and The Curse of Frankenstein. Guardian of Piri features the Space: 1999 debut of Catherine Schell as the siren-like Guardian, whose alluring presence brings death for all who cross Piri's path. Schell would go onto join the series from Year 2 as the metamorphically Maya. Future Lovejoy and John Wick star Ian McShane plays the doomed Alphan Anton Zoref in Force of Life, who is ensnared by an otherwise neutral entity intent on maintaining its existence by feeding off of whatever source of heat it can consume - including passing human beings. 

Reliable cinematic rogue Julian Glover portrays the villainous Jarak in Alpha Child, intent on murdering Moonbase Alpha with his hypnotic powers. Glover is famed for his portrayals as any number of memorable enemies from Quatermass and the Pit to Star Wars, Doctor Who, Indiana Jones and the Last Crusade and even a late-career highlight in Game of Thrones. TV/film veteran Alex Scott makes a brief but memorable appearance as Aarchon in Voyager's Return, his role as the desperate yet vengeful alien enlivens the dramatic reveal of the destructive power of the returning Voyager shuttle to Moonbase Alpha.

Collision Course features the final onscreen performance of celebrated stage actress and BAFTA award-winning Margaret Leighton as the mysterious Queen Arra, guiding Koenig on Moonbase Alpha's strange destiny through the cosmos. Although apparently struggling to comprehend her metaphysical dialogue, Leighton maintained a deeply immersive performance. Brian Blessed and John Shrapnel deliver a compellingly clashing duelling performance in Death's Other Dominion, one deceptively charming, the other sympathetically unhinged. While neither of these characters are especially alien, Dr. Cabot Rothwell's inhumane efforts to achieve immortality breaks down barriers of human definition - as evidenced by Colonel Jack Tanner's mentally broken state.

One particular fan became so enamoured by Peter Bowles' performance as the murdering psychopath Balor in End of Eternity that she wished to be dominated by, as Bowles himself put it, the most evil man in the universe. Isla Blair (wife of Julian Glover) turns a weirdly watchable performance as the stoic female alien in War Games., alongside Anthony Valentine. Caroline Mortimer (Juggernaut, The Pallisers, Kids, The Saint) and Kevin Stoney (The Adventures of Robin Hood, Doctor Who, Freewheelers, The Power Game, The Avengers, Blake's 7) bring warring antics that threaten the entire Moon in The Last Enemy.

Leo McKern delivers a rapturously haunting performance in The Infernal Machine as both the mechanically sentient Gwent and its humanoid companion, both of them trapped in an absurdly volatile relationship of co-dependency. Outside of equally memorable roles in cult tele/film gems such as The Prisoner, X the Unknown, and The Day the Earth Caught Fire, his most recognisable role was that of Horace Rumpole in Rumpole of the Bailey between 1978 and 1992. Dennis Burgess (Father Brown, The Sandbaggers, Triangle) and Aubrey Morris (The Champions, Danger Man, The Prisoner, A Clockwork Orange, The Wicker Man) star alongside Hollywood icon Joan Collins in Mission of the Darians as survivors of a dying alien race whose fate becomes entangled in the Alphans' own journey for survival.

Year 2

Year 2's reliance on a more modest core cast and greater inclusion of human characters to carry episodes meant that expressively otherworldly, and expensive, guest stars were less relied upon. Year 2 does boast a handsome array of recognisable onscreen talent. The Metamorph brings Brian Blessed and Catherine Schell back into the Space: 1999 universe, this time in different roles. In this classic debut of Space: 1999's controversial reinvention, maniacal and deceitful Mentor hides a terrible secret from his shapeshifting daughter, Maya, in bringing their home world of Psychon back to life.

Stacy Dorning, fresh from The Adventures of Black Beauty, and experienced stage actor Peter Duncan join forces for The Exiles, an episode which has its origins in being initially written in the more downbeat Year 1 format. BAFTA-winning actress Billie Whitelaw portrays the android Zamara in One Moment of Humanity, seeking the answer to experiencing violent emotions to rid themselves of their human masters. She took the role not for any great affection she held for the series, but because her son was quite the fan instead.

The stoutly-formed Willoughby Goddard performs a memorable role as the Lothario-like Taybor, keen to exchange riches from across the universe, but he soon becomes ensnared by what he sees as the greatest treasure of all - Maya. David Jackson (Z-Cars, The Saint, The Avengers, Blake's 7, Only Fools and Horses) does his utmost to make a clutch of judgemental trees sound as dangerous as possible in The Rules of Luton. He also stars alongside Roy Marsden and Godfrey James as the marauding alien prisoners fighting against the entrapped Maya and Koenig. Olivier-nominated stage actor John Standing gives a dangerously taught role as the infected Pasc in The Mark of Archanon, while the lesser-known Michael Gallagher portrays his son, Etrec. Gallagher's performance was subjected to additional voiceover work by an uncredited actor. 

In-between his iconic performances in The Wombles and Fawlty Towers, Bernard Cribbons turns a charming performance as the deceptively welcoming computer Brian in Brian the Brain. Cribbins preferred to perform his dialogue live on set, rather than add his voice for post-production, eliciting a more natural and believable performance. Former racing driver, boxer and horror icon Guy Rolfe performs as the cosmic magician Magus in New Adam New Eve, who sets about convincing the Alphans he is in fact God. A pre-Star Wars David Prowse suffers the ignominious act of getting whacked in the groin by Tony Anholt in The Beta Cloud in which he plays an unnamed rampaging creature who breaks into Moonbase Alpha.

An ensemble consisting of Tony Robins (For Your Eyes Only, The Saint, The Protectors), Stuart Damon (The Champions, UFO, The Saint, The New Avengers, General Hospital), and Patrick Westwood (The Quatermass Experiment, Poldark, Jason King, Dixon of Dock Green, Department S) leads The Bringers of Wonder, portraying human cadavers of an invading species of disguised blob-like aliens intent on overtaking Moonbase Alpha.

Lee Montague, a regular face on ITC spy-fi works (Danger Man, The Baron, Department S) and Jill Townsend (The Protectors, Bonanza, Cimarron Strip, The Sweeney, The Girl from U.N.C.L.E.) command Dorzak. Townsend was struck by suspected flu during her performance, but soldiered on in spite of her pain, which transpired to be appendicitis. Like a lot of Year 2's guest actors, Montague boasted an impressive stage history, along with being the first ever storyteller on Jackanory.

Hildegard Neil (Anthony & Cleopatra, Doomwatch, Jason King, Ace of Wands, The Protectors, The Professionals), wife to Brian Blessed, portrays the sadistic Elizia alongside Roy Marsden's Crael in Devil's Planet. Jordanian-British actor Nadim Sawalha father of Julia and Nadia Sawalha, invokes a compelling desperation in The Immunity Syndrome as the doomed Zoran. Former Doctor Patrick Troughton leads Space: 1999 in its swansong episode, The Dorcons, as the aging ruler Archon, who plots to exploit Maya's genetical make-up to preserve his own race.

Space: 1999's blend of Hollywood legends and cult TV icons all bring their uniquely immersive performances in bringing to life some of the most dangerous, powerful, terrifying or otherwise downright strange alien creatures experienced by Moonbase Alpha!  

Experience Brian Blessed and Catherine Schell's beloved performances as Mentor and Maya like never before with the Space: 1999 The Metamorph 4K Collectors Edition Steelbook, available now! You can also see the episode and Breakaway on the big screen as part of the Square Eyes TV Festival in Birmingham on 12th November - get your tickets now for this out-of-this-world cinematic screening!