Muriel Spark gave sustained attention to the problem of evil. In her view, people committed evil acts gratuitously, merely for the sake of causing suffering. By the same token, novels are virtually unthinkable without some degree of evil—or evil in its lesser forms, such as mischief, wickedness, or wanton cruelty. Using previously untapped archival materials, this chapter focuses on manifestations of evil in two of Spark’s novels: The Comforters, in which evil is an intrusion on privacy, and Memento Mori, in which the evil characters, Mabel Pettigrew and Eric Colston, manipulate, blackmail, and threaten others for personal gain. Spark’s speculations on evil must be understood in terms of philosophical and theological discussions at mid-century. For Spark, evil was not a psychological issue so much as a moral one. In this regard, her novels can be profitably read alongside works about evil by C. E. M. Joad, Jean Nabert, and Hannah Arendt.