This chapter collects a number of subjects of theoretical investigation that fall under the heading of “the nonhuman turn,” that is, the move in contemporary theory to break out of the confines not only of the linguistic turn but also of the anthropocentrism that has more or less defined the critical project from its inception. As a result, recent theorists have been empowered to attend not just to textual representations of animals, affects, objects, and environments, but to theorize directly about their ontological constitutions. After reviewing how the nonhuman turn came about, this chapter looks specifically at three theorists at its forefront: Donna Haraway, whose two manifestos on cyborgs and companion species are widely cited; Sara Ahmed, whose work draws on postcolonial theory, phenomenology, affect theory, and of course feminism; and Timothy Morton, whose interventions into ecological criticism have been transformed by his adoption of the new philosophical methodology called object-oriented ontology. These theorists’ ideas are then applied to texts by Mary Shelley, Jeff VanderMeer, and Margaret Atwood.