This chapter argues that the witches in Dario Argento’s Suspiria (1977), Inferno (1980), and Mother of Tears (2007) operate in the manner of endoparasites. The first film focuses on Mater Suspiriorum, the ancient mistress of a dance school, the interiors of which resemble some of our major organs and make the coven members in them seem a sort of cardiopulmonary infection. The sequel introduces Mater Tenebrarum, who creeps about the secret chambers of a New York mansion; these rat-ridden and near-underwater spaces speaks to the skeletomuscular form of infection that she represents. The final film, Mother of Tears, features Mater Lachrymarum, who obtains a magic tunic and uses it to foment chaos in museums, train stations, and other metropolitan areas. The stress on the enteric, as well as the film’s splatter effects, figure the witch as a sero-intestinal form of endoparasite.