Arm all lasers, Alphans! 50 years since its debut, Space: 1999 continues to enthral viewers with its imaginative spectacle of the petrifying horrors that await in the deepest recesses of the universe. Space: 1999 may present audiences with the awe-inspiring qualities of outer space, but it also features an abundance of scarily unhuman characters.

From the visually disgusting to the thematically overwhelming, let's celebrate both Space: 1999's 50th anniversary and the spooky season by counting down the series' most terrifying aliens!

10. The Blobs (The Bringers of Wonder)

These creatures are sure to split opinion! What may have terrified you as a child may be easy to snort at now in derision, but the Blobs, as they were named in Terence Feely's script for the Year 2 two-parter The Bringers of Wonder, come painfully close to bringing certain destruction to Moonbase Alpha. What the Blobs lack in agility, they easily make up for in repulsive appearance and towering scale. Keith Wilson's concept art is quite faithfully replicated into something nauseatingly grotesque, complete with pulsating organs, fleshy tendrils, and flowing bodily fluids.

9. Invisible being (The Immunity Syndrome)

One of Year 2's most terrifying adventures defies the stereotypes of Space: 1999's second series serving as a lesser beast compared to Year 1. Moonbase Alpha's discovery of a seemingly perfect planet for human habitation slips into chaos when numerous Alphans succumb to extreme bouts of violence. The planet itself appears to be rejecting its newfound occupants, and only through drastic attempts at communicating with the planetary intelligence can the Alphans hope to save themselves. While the mysterious entity within the planet remains unseen, its invisible nature and awesome power lends it a creepily unknown quality.

8. Dorzak

A tensely coiled mystery surrounds the arrival of Dorzak, prisoner of humanoids emissaries from the planet Novah and former friend of Maya, who is thrilled at the knowledge that she's no longer the last living Psychon in the universe. Surely it can't be true that the peaceful, philosophically minded Dorzak has turned to violence and hatred? Christopher Penfold's one and only contribution to Year 2 delivers a story full of sombre pathos that eloquently depicts a character's fall from grace into becoming a villain, not out of evil, but out of survival. The quietly dignified nature of Dorzak is countered by his destructive qualities. 

7. Kalthon consciousness (Seed of Destruction)

Another decidedly spooky effort from Year 2 sees the self-destructive nature of pursuing survival to its most extreme rear its head once more when an evil doppelganger of Commander Koenig is replicated to trigger the alien lifeforce secluded within a dormant asteroid made of crystal back to life. The nature of using an evil clone of Koenig and the invisible nature of the Kalthon alien conveniently removes the need for any physical alien being during the episode, but the eerie crystal asteroid setting which entraps Koenig and replicates him is nervously distorting. The grandiose nature of the otherwise immobile yet fiercely intelligent Kalthon consciousness is another showcase of the dangerous menaces that surround Moonbase Alpha.

6. Gwent (The Infernal Machine)

In a fantastically compelling dual performance from Leo McKern, the lines between man and machine are chillingly blurred with the stupendously strange Gwent, a curiously defined mechanical being which captures Koenig, Russell and Bergman to be its new humanoid companions when its previous one succumbs to death. In a episode brimming with theatrical aplomb, the trio of Alphans must navigate the surreal interiors of the deafening Gwent, who appears as a disembodied creature, yet whose true form lends The Infernal Machine and astoundingly fearful quality of the depths we may go to preserve our physical selves. 

5. The Guardian (Guardian of Piri)

Catherine Schell delivers an appropriately alluring performance as the siren-like Guardian of the planet Piri, a seemingly ideal world in which all of life's drawbacks appear to have been eradicated. All but Koenig fall under her spell, which reveals to be a form of slow decay in which the Alphans are at risk of being consumed by total, blissful apathy. The Guardian's true form is eventually and dramatically revealed, putting a new and shocking spin on the idea of physical perfection.

4. Unknown alien (Force of Life)

The lengths non-human life will go to survive in the vacuum of space continue to provoke horrifying phenomena within the confines of Moonbase Alpha. In Force of Life, a wandering spec of cosmic life finds an unwitting host within nuclear technician Anton Zoref, who proceeds to be overcome by the primal need to consume heat. Represented only by a single blue sphere, the unnamed alien intelligence which overpowers Zoref to become its host results in the near total annihilation of Alpha. Scary in its simplicity, the unnamed alien's takeover of Zoref isn't derived from malice, but purely to advance its own evolutionary cycle. Yet it produces some of Space: 1999's visually terrifying scenes, in which ice-induced death ripples through Alpha.

3. Unnamed aliens (War Games)

The scariest alien enemies Space: 1999 had to offer? Perhaps not. But the unnamed aliens from the classic Year 1 anti-war parable War Games are certainly the most judgemental. They torture the Alphans, John and Helena in particular, with intensely realistic imagery of all-consuming destruction, dragging Moonbase Alpha towards a chaotic and unstoppable death. This is done so in judgement that Moonbase Alpha's odyssey within the cosmos is akin to that of a virus spreading itself across the stars. These omniscient aliens ultimately deliver a violent warning of how humanity's war-mongering ways will ultimately seal their own fate.

2. Balor (End of Eternity)

While not held in high regard by scriptwriter Johnny Byrne, End of Eternity delivers one of Space: 1999's most charismatically alien enemies. Byrne would later state that indestructible murderer Balor's lack of convincing backstory dragged the episode down in his estimations, yet it also lends him and the episode a striking immediacy. Shorn of metaphysical wanderings, here we have a villain who loves killing for the pure thrill of killing itself. It's pleasingly simple approach that elevates Balor to become an enjoyably memorable antagonist for Moonbase Alpha.

1. The Dragon (Dragon's Domain)

Was there really any chance the number #1 spot would be any other of Space: 1999's most grimly frightening creatures? Any number of Space: 1999's alien monsters can be argued to boast horrifying qualities, yet the tentacled creature from Dragon's Domain is the only one to be purposefully framed as a living nightmare. Such is the vastness of this hellish being that it can't be fully witnessed onscreen, and all who dare to slip into its path are sickeningly consumed. The dragon personifies the frighteningly opaque nature of the universe that Moonbase Alpha is forced to travel through. Whatever mystical quest Alpha may be on, there's no sure way to determine what kinds or how many unknowable horrors may be lurking within the stars, waiting to draw the Alphans into their destructive path!

Celebrate Space: 1999's 50th anniversary with our spectacular range of events and releases! Shop our Breakaway 2025 Collection for a superb range of Space: 1999 books, Blu-rays, models and more. Check out the brand new celebratory documentary Space: 1999: 50 Years Out of Orbit on ITVX. You can also discover the sprawling history of Space: 1999's merchandise at the Museum of Brand's Gerry Anderson exhibition: Thunderbirds and Space: 1999: A Celebration of Toys and Collectables! 

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