As Ian Holm tells the crew of the Nostromo before sputtering out of juice, the Alien is the "perfect organism". "It's structural perfection is matched only by its hostility … I admire its purity." He had a point. The creature in Alien and its many spin-offs was, and still is, one of the most genuinely alien things the movies have ever given us – the perfect movie monster.
Up to that point in 1979, screen horrors were still very much of this earth: psycho-killers, werewolves, spirits, sharks, that sort of thing. Suddenly, here was a creature both incomprehensible and relatable. It had a biological credibility, with its acid for blood and its bizarre, parasitic life cycle. It looked like an egg, then a sort-of crustacean, then, ultimately, one of us. Or a hideously deformed reflection of us, with its oversized head, its spindly limbs, its lack of eyes, its telescopic jaw. Like every great monster, Alien chimes with our deepest fears – death, sex, bodily violation, all iced over with the chill of the uncanny.
It took an out-there imagination to dream it up, and HR Giger was undoubtedly the man for the job. Apparently even other crew members were spooked on set by this softly spoken Swiss man, who dressed all in black and preferred to loiter, Dracula-like, in the shadows. There were rumours he kept the bones of his dead wife, Li Tobler, in his studio. They turned out to be untrue, though Giger was very much in touch with the dark side. As a child, he claims to have been beset by regular nightmares. Tobler, the model for many of his early works, had committed suicide in 1975, after an apparently tumultuous and bohemian marriage. That only fed further into his disturbing visions. Alien's co-writer Dan O'Bannon later recalled meeting Giger for the first time, in a Paris hotel. Giger offered him some opium. O'Bannon asked why he took it. "I am afraid of my visions," Giger replied. "It's just your mind," O'Bannon said. Giger responded: "That is what I am afraid of."
Before Alien, Giger primarily considered himself an artist. It was at an exhibition in Paris in the mid-1970s that he was spotted by another psychedelic visionary, Alejandro Jodorowsky, and co-opted into the movie industry. The story of Jodorowsky's unmade Dune project is the stuff of legend (and documentary – Frank Pavich made an entertaining film about it last year). Before it fell apart, Jodorowsky had assembled a host of talents including French comics scion Moebius, British sci-fi illustrator Chris Foss and writer/special effects Dan O'Bannon. Not to mention a cast including Orson Welles, Gloria Swanson and Salvador Dalí.
It was O'Bannon who brought Giger on to Ridley Scott's movie, and the rest is movie history, but Giger's commercial success all but destroyed his credentials as a fine artist. By the 1970s, he had established an aesthetic he never deviated from: disturbing, obscene fusions of machine-like parts, women's bodies, skulls, bones, weapons, teeth, tentacles, occult symbology. Not a particularly novel iconography, you could say, but it was really about the execution. He's often associated with surrealists such as Dalí or doomy symbolists like Arnold Böcklin (Giger once did a homage to Böcklin's famous Isle of the Dead), but Giger's precisely detailed, airbrushed, colour-leached style was all of its own, bringing to mind ancient temple carvings, the elegant lines of art nouveau, and modern technical drawings.
Giger's imprint can be seen in countless subsequent attempts to imagine aliens and alien worlds, but the movies have yet to come up with anything as bracingly terrifying as Alien. His iconography has also been adopted wholesale by gothic subculture, which has diminished its impact somewhat. Rather than the dark reaches of the human psyche, Giger's imagery is now more likely to bring to mind tattoo parlours, fetish clubs and 1990s cyberpunk. In his later career, his work also devolved into semi-pornographic self-parody, it must be said. But having created an aesthetic unique enough to earn its own adjective, it would be unfair to demand more of Giger. He's done plenty enough. He seems to have genuinely gazed into the abyss. What he brought back was mercifully filtered through a refined visual sensibility. "Sometimes people only see horrible, terrible things in my paintings," Giger once said. "I tell them to look again, and they may see two elements in my paintings – the horrible things and the nice things."
• Sci-fi surrealist HR Giger, creator of Alien visions, dies in fall
• HR Giger's alien visions – in pictures