Michel Foucault (1926 - 1984) was a major figure in two successive waves of twentieth century French thought--the structuralist wave of the 1960s and then the poststructuralist wave. By the end of his life, Foucault had some claim to be the most prominent living intellectual in France.

Foucault’s work is transdisciplinary in nature, ranging across the concerns of the disciplines of history, sociology, psychology, and philosophy. At the first decade of the 21st century, Foucault is the author most frequently cited in the humanities in general. In the field of philosophy this is not so, despite philosophy being the primary discipline in which he was educated, and with which he ultimately identified. This relative neglect is because Foucault’s conception of philosophy, in which the study of truth is inseparable from the study of history, is thoroughly at odds with the prevailing conception of what philosophy is.

(from the Internet Encyclopedia of Philosophy)