alien is a 1979 british-american science fiction–horror movie directed by ridley scott. it is called a science fiction movie because the story takes place in outer space, and there are alien creatures. the movie's title refers to a highly aggressive (angry) and intelligent extraterrestrial (alien creature) that attacks and kills the crew of the spaceship "nostromo". the movie stars sigourney weaver as ellen ripley, tom skerritt as captain dallas, and ian holm as ash.