José Guilherme Merquior (Rio de Janeiro, April 22, 1941 — Rio de Janeiro, January 7, 1991) was a Brazilian diplomat, academic, writer, literary critic and philosopher. He divided his published works in two segments; in one the bulk was criticism per se; in the other the emphasis was the history of ideas, or more specific investigations like the highly-esteemed study of Rousseau and Weber. He was a major supporter of the Fernando Collor de Mello government and wrote many of Collor's public speeches.
He was a prolific writer, and member of the Academia Brasileira de Letras (the Brazilian Academy of Letters). He had a doctorate in sociology from the London School of Economics, which was directed by Ernest Gellner. Merquior also studied under Lévi-Strauss, and took guidance from the likes of Raymond Aron, Harry Levin, and Arnaldo Momigliano. He published books written directly in French, English, Italian, and his native Portuguese.