From Carrie and Rosemary's Baby to Us, Hereditary, and Run, the image of the mentally ill mom as villain looms large in the horror genre. What do these movies communicate about mothers living with mental illness, and how do these depictions affect them? Portraying mentally ill moms as problems to be overcome, often by their own children, perpetuates harmful stereotypes with potential real-world consequences, such as the belief that these women are unfit to bear or raise children. More compassionate representations are needed to lessen the social stigma associated with the mentally ill. Fortunately, some of the more contemporary horror films are attempting to achieve that task with critical success. Using case studies from a broad range of films, including the classic, campy, slasher, or prestige, and placing them within their historical context, this work extends conversations about horror and mental illness, such as post-partum depression, bulimia, Munchausen by proxy syndrome, and others. Highlighting the trope of the mentally ill mother as a pervasive image within the genre furthers examination of how these films challenge or reflect existing stereotypes and illustrates how horror can be both a site of oppression and a source for positive transformation.