Nicolás Guillén's "El gran zoo" (1967), illustrated by Fayad Jamís, was the first Hispanic bestiary to prominently feature humans in a space traditionally inhabited by beasts. Guillén's verses transform the bestiary from a didactic tool used for centuries to instruct and uniform society into a subversive text that openly denounces the injustices and idiosyncrasies of Cuban and American life in the 1960s. The portrayal of humans in bestiaries, independent of historical context or narrative aim, raises several biopolitical questions, with the most significant being: How are "persons" and "nonpersons" constructed? This article explores the consequences of Guillén's choice to place humans where beasts once resided, as well as his impact on three subsequent bestiaries: "Bestiario de historia mexicana" (2010), by Julián Meza, "200 años de monstruos y maravillas argentinas" (2015), by Gabo Ferro, Christian Montenegro, and Laura Varsky, and "Bestiario médico" (2000), by Carlos Ferrándiz and Carlos Baonza. Through a biopolitical lens, the article will analyze the mechanisms employed when constructing human animals, beasts, or monsters, (human "nonpersons"), as well as the precarious scaffolding on which this ideology rests.