Pierre Marie Félix Janet (May 30, 1859 - February 24, 1947) was a pioneering French psychologist, philosopher and psychotherapist in the field of dissociation and traumatic memory.

He was one of the first people to draw a connection between events in the subject's past life and his or her present day trauma, and coined the words ‘dissociation’ and ‘subconscious’. He studied under Jean-Martin Charcot at the Psychological Laboratory in Pitié-Salpêtrière Hospital, in Paris. In several ways, he preceded Sigmund Freud. Many consider Janet, rather than Freud, the true 'founder' of psychoanalysis and psychotherapy.

He first published the results of his research in his philosophy thesis in 1889 and in his medical thesis, L'état mental des hystériques, in 1892. He earned a degree in medicine the following year in 1893.

In 1898, Janet was appointed lecturer in psychology at the Sorbonne, and in 1902 he attained the chair of experimental and comparative psychology at the Collège de France, a position he held until 1936. He was a member of the Institut de France from 1913.

In 1923, he wrote a definitive text, La médecine psychologique, on suggestion and in 1928 - 32, he published several definitive papers on memory.

While he did not publish much in English, the fifteen lectures he gave to the Harvard Medical School between 15 October and the end of November 1906 were published in 1907 as The Major Symptoms of Hysteria and he received an honorary doctorate from Harvard in 1936.