The film was almost called Star Beast. And if it had been, it may never have grown to become the creature we know today. Thankfully, its writers settled on Alien - a title that lent the terrifying tale of the unknown an appropriately unsettling feel. But it was much more than a simple name change that elevated Ridley Scott's 1979 movie above its peers.
Spawning three direct sequels, two spin-off movies and now a prequel in Prometheus, the Alien mythology is more popular today than ever before. Why? Because of the way its ideas seem to attach themselves to us like the story's facehuggers, disabling our nervous systems and feeding directly into the primal areas of our brains.
Alien addressed sexuality and sexual fear like no horror film before it. The movie and its sequels also challenged preconceptions of gender, with its protagonist Ellen Ripley (Sigourney Weaver) the perfect feminist heroine, as strong and capable as her male counterparts - if not more so - but compassionate and vulnerable, too. The film also benefited from a visual aesthetic that placed it in a world that we could believe in, from the grimy corridors of the leviathan-like spaceship Nostromo, to the unnervingly organic design of the alien creatures themselves.
It owed a debt to 1951's The Thing From Another World, about a group of isolated workers who discover a long-dormant creature, which then picks them off one by one. Alien's writers Ronald Shusett and Dan O'Bannon pitched the idea as "Jaws in space", but their story's central conceit had something that neither of these films could compete with.
Responding to a distress call on an unknown planetoid, the crew discover a nest of mysterious eggs. When a creature suddenly springs to life and attaches itself to one of their member's faces, the workers break quarantine and bring it aboard. But we soon learn that the facehugger was just an intermediary, living for the sole purpose of inseminating the man. A worse horror begins later, as a far more dangerous creature bursts from his chest, born of blood and chaos.
It's this apparent perversion of nature that gave Alien its power, and proved so captivating to audiences and filmmakers that they kept going back for more. The film's action-driven sequel, 1986's Aliens, may have lost some of the original's carnal effectiveness, but by forcing Ripley to face off against an egg-laying alien queen in its climactic scene, it added another strand to the matriarchal mythos.
Ideas alone don't make great movies, however. The Alien saga is made all the more compelling by Weaver's nuanced and relatable performance, as well as Scott and the Aliens filmmaker James Cameron's near-faultless direction. Worthy of particular acclaim is HR Geiger, the Swiss surrealist artist from whose mind the grotesque but oddly beautiful creatures sprang.
Now returning to the series after 33 years with Prometheus, Scott has remained tight-lipped about exactly how the story will relate to his original nightmare. But with a new female lead in Noomi Rapace and the promise of as-yet-undiscovered terrors lurking in the dark, it seems he hasn't forgotten what made Alien great to begin with.