This article examines the 1979 adaptation of Ridley Scott's Alien. It focuses on the way the adaptation process results in two works with very different generic mix. Both the film and the comics can be read a generic hybrid, belonging both to horror and science fiction, but the balance is different. The article argues that the constraints of the comics form make it impossible to adapt the established grammar of horror cinema—especially the effect of surprise—which leads to the observed shift in generic affiliation. This leads to a broader argument on the effect of adaptations on genre.