"Alien is all about “the dark side of technology, of science,” says David J. Skal, author of “The Monster Show: A Cultural History of Horror.” “Despite all the things we’re told that will make the future a better place, what happens in Alien is our worst nightmare.” That’s exactly what Dan O’Bannon was thinking when he set out to write what he calls “a scary spaceship movie” in the mid-1970s. Influenced by 1950s sci-fi films like “The Thing,” O’Bannon was determined to make a “monster thriller about a monster from outer space, done with the style and technology that had accumulated since the 1950s.” This merger of horror and science fiction proved extremely fortuitous. There had been plenty of monsters in movies before Alien, but mostly they had been of the “man in a rubber suit” variety. Thanks to the creepy vision of Swiss artist H.R. Giger, the extraterrestrial monster in Scott’s film, with its insect-like body, acidic blood and knife-sharp teeth, was truly nightmarish."