At its most fundamental level, "Alien" is a movie about things that can jump out of the dark and kill you. It shares a kinship with the shark in "Jaws," Michael Myers in "Halloween," and assorted spiders, snakes, tarantulas and stalkers. Its most obvious influence is Howard Hawks' "The Thing" (1951), which was also about a team in an isolated outpost who discover a long-dormant alien, bring it inside, and are picked off one by one as it haunts the corridors. Look at that movie, and you see "Alien" in embryo.