This talk is about the history of European notions of what it meant to be human between the late Middle Ages and the Scientific Revolution. I argue that the category of human was shaped by the category of the monster, and show how practices of classifying and describing monsters in different textual traditions changed notions of the boundaries between human, monster and animal. Three case-studies I examine in this talk are the werewolf, the headless people of Guiana described by Sir Walter Raleigh, and the Patagonian giant. By analyzing both monsters within Europe and monsters in distant places, I show how the divisions between self and other were re-shaped by artisans and scholars through multiple textual and visual genres. In so doing, I show how the concept of the monster is essential for understanding the longue durée history of racial science, and the ways in which early modern science was a visual pursuit. I also underline the importance of expanding the themes that we deem to constitute ‘science’ in order to better understand attempts to make sense of the natural world in different periods and places.