Sigmund Freud was an Austrian neurologist and the founder of psychoanalysis, a clinical method for evaluating and treating pathologies seen as originating from conflicts in the psyche, through dialogue between patient and psychoanalyst. Freud's work has profoundly influenced modern psychology, psychiatry, psychotherapy, and popular culture.

Freud was born to Galician Jewish parents in the Moravian town of Freiberg, in the Austrian Empire. He qualified as a doctor of medicine in 1881 at the University of Vienna. Upon completing his habilitation in 1885, he was appointed a docent in neuropathology and became an affiliated professor in 1902. Freud lived and worked in Vienna, having set up his clinical practice there in 1886. Following the German annexation of Austria in March 1938, Freud left Austria to escape Nazi persecution and died in exile in the United Kingdom in 1939.

Freud developed therapeutic techniques such as the use of free association and discovered transference, establishing its central role in the analytic process. His analysis of dreams as wish-fulfilments provided him with models for the clinical analysis of symptom formation and the underlying mechanisms of repression. Freud elaborated his theory of the unconscious and developed a model of psychic structure comprising the id, ego, and super-ego. He also postulated the existence of libido, a sexualized energy that influences mental processes and structures, and a death drive, the source of compulsive repetition and aggression.

Freud's theories, though controversial, have left an indelible mark on Western thought and continue to be the subject of extensive debate regarding their efficacy and scientific status. In 1930, Freud was awarded the Goethe Prize for his creative work. A lunar crater has been named in his honor.