Links: TVTropes (entire series), Wikipedia, IMDB (8.5).
A now-classic sci-fi horror film that rewrote the genre. The direction and editing is notable for slowly building tension without hurting the pacing of the movie, H. R. Giger's artwork manages to provoke the audience in ways that you'd never think a human in a rubber suit could do, and of course the film introduced the world to Sigourney Weaver's acting talents. Even in the finished product, there are some places where the pacing bogs down a bit, and the growth rate of the alien results in some forehead-slapping among scientifically-minded viewers, but the overall result is quite good. Score: 4 stars out of 4.