The most effective monsters of horror fiction mirror ancestral dangers to exploit evolved fears. For most of human evolutionary history, we have faced threats in the domains of predation, conspecific violence, contagion, status loss, and dangerous nonliving environmental features. We thus very easily acquire fears directed toward threats from these domains. This chapter argues that the nonrandom distribution of human fears is reflected in horror, which features stimuli that mirror evolved fears, often in incarnations that are exaggerated and/or counterintuitive for increased salience, including giant spiders, supernormal monsters such as evil clowns, and physics-violating ghosts. Many monsters are also equipped with contagion cues, thus exploiting an evolved disgust mechanism. Some monsters evoke moral disgust through their violation of norms. To strengthen audiences’ emotional responses to such monsters, horror artists often provide descriptions of characters’ reactions which are mirrored by the audience through an adaptive mechanism enabling emotional contagion.