Herbert "Harry" Stack Sullivan (February 21, 1892, Norwich, New York – January 14, 1949, Paris, France) was an American Neo-Freudian psychiatrist and psychoanalyst who held that the personality lives in, and has his or her being in, a complex of interpersonal relations. Having studied therapists Sigmund Freud, Adolf Meyer, and William Alanson White, he devoted years of clinical and research work to helping people with psychotic illness.