In “Extinction,” Timothy Sweet explores how species extinction and the ultimate specter of human extinction shape modern literature and theory. The chapter begins with an overview of the Sixth Extinction crisis, which was first recognized by scientists in the 1980s and has since become a matter of public concern in journalism and memoir. The chapter then focuses on the history of the concept of extinction from its establishment as geohistorical fact in the late eighteenth century to its role in the development of evolutionary theory. An important archive for the chapter is the repository of megafaunal remains from Big Bone Lick, Kentucky. Alternative explanations for these extinctions and other fossil remains circulated in American Indian traditions, and later versions adapted Darwinian theory to traditional ends. The chapter ends with examination of literary and artistic works such as Barbara Kingsolver’s Flight Behavior that grapple with the problems of representing the extinction of animals and humans.