“You nevertheless never realize what you are dealing with, do you?” That is the well-known problem posed by Ash (Ian Holm) in just one of the numerous tense scenes of Ridley Scott’s 1979 film Alien. Ash goes on: “Perfect organism. Its structural perfection is matched only by its hostility… Unclouded by conscience, regret, or delusions of morality.” Holms’s character is describing the darkish creature at the heart of Scott’s masterpiece, an extraterrestrial dubbed the xenomorph. This unforgettably terrifying alien set a new bar for cinematic angst about deep space and existential dream—one that, some argue, has not been matched in the additional than 40 years given that the film’s launch. The otherworldly development has…