Pierre Clastres (French: [klastʁ]; 17 May 1934 – 29 July 1977) was a French anthropologist and ethnologist. He is best known for his contributions to the field of political anthropology, with his fieldwork among the Guayaki in Paraguay and his theory of stateless societies. An anarchist seeking an alternative to the hierarchized Western societies, he mostly researched indigenous people in which the power was not considered coercive and chiefs were powerless.