Jacques Lacan was a French psychoanalyst and psychiatrist known for his influential contributions to psychoanalysis. He developed a unique approach to the field, which he named 'Lacanian psychoanalysis,' emphasizing the role of language and the unconscious in shaping human behavior. Lacan's seminars and writings had a significant impact on the fields of psychology, philosophy, and literary theory, challenging traditional psychoanalytic theories and introducing innovative concepts such as the mirror stage.