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 "personality can never be isolated from the complex interpersonal relationships in which [a] person lives" and that "[t]he field of psychiatry is the field of interpersonal relations under any and all circumstances in which [such] relations exist". 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.