And it offered psychosexual subtext aplenty to chew over long after the beastie had been ejected into space, only for its many cousins to turn up in Aliens, James Cameron's superbly gung-ho expansion on the original.
Then they just kept coming back in Alien3 and Alien Resurrection, the confused movies which gave Ripley two last stands that made you wonder if its respective creators had actually seen the original.
Scott's first Alien transcended its B-movie space-horror origins care of its design, pacing, and Weaver's performance.
Here though, Scott and his writers (which includes Damon Lindelof from TV's Lost ) are reaching for far bigger ideas than simply how to survive a bad bout of face-sucking space parasites.
Their starting point is the big dead "space jockey" with the gaping hole in its chest that was aboard the drifting spaceship that Ripley's Nostromo unwisely docked with.
Set 30 years earlier, Prometheus emerges not so much as Alien's older testament but a film which is attempting its own cosmic thesis about life, the universe and everything, in between working its way through a predictable list of alarming discoveries and clunky dialogue.
Sometimes it manages a combo of both: "Miss Vickers, is there an agenda you are not telling us about?"
That's an early question from otherwise brilliant scientist Dr Charlie Holloway to Charlize Theron's icy corporate bitch. The inquiry comes a little after they've landed on a moon in another galaxy on the spaceship of the title paid for by the Weyland Corporation.
They're there because his archaeological work with boffin partner Dr Elizabeth Shaw (Rapace) indicated it's the right address to find out Something Important about where life on Earth came from.
Their theory, which forms the movie's startling, if disconnected, prologue, will sound a little familiar to anyone who's read Erich von Daniken's Chariots Of The Gods or stayed awake to the end of Indiana Jones and the Crystal Skull.
As the brilliant Shaw, Noomi Rapace is designated the surrogate Ripley of the piece. But she's really not able to shoulder the centre of the film as everything collapses around her and the rest of the expedition are dispensed with, roughly in order of how irritating they are.
Characters aren't a strong point here. Some, like Holloway, function as enablers to plot points, while many just make you wonder about Weyland Corp's HR policies. That said, a few do shine through, like Idris Elba's captain who pilots the ship standing at his console looking like a DJ from another galaxy.
And then there's Michael Fassbender's android David, who easily matches Alien's resident synthetic personnel Ash or Aliens' Bishop for otherworldly presence.
He does that resembling a mix of David Bowie and Peter O'Toole in Lawrence of Arabia (the David Lean movie is referenced both here and in a viral video showing corporate boss Peter Weyland as a younger man earlier in the 21st century).
David and his mixed motives are one of the film's strongest elements, even if he winds up suffering the trademark indignities that always befall the inorganic folk in Alien movies.
But this really isn't an Alien movie; it's a lumbering, if visually impressive, space exploration epic which eventually turns into an Alien movie.
It should still leave the fit-to-burst fanclub vaguely satisfied and it's certainly an improvement on parts III and IV.
But Prometheus' higher aims still make for lower thrills.
Stars: 3.5/5 Cast: Noomi Rapace, Michael Fassbender, Charlize Theron, Guy Pearce Director: Ridley Scott Rating: R16 (violence) Running time: 124 mins Verdict: Alien prequel grander but blander
