William S. Breitbart, FAPM (born 1951), is an American psychiatrist in Psychosomatic Medicine, Psycho-oncology, and Palliative Care. He is the Jimmie C Holland Chair in Psychiatric Oncology, and the Chief of the Psychiatry Service, Department of Psychiatry and Behavioral Sciences, Memorial Sloan-Kettering Cancer Center (New York, NY), He is a Professor of Clinical Psychiatry at Weill Medical College of Cornell University. He was president of the Academy of Psychosomatic Medicine, and the Editor-in-Chief of Palliative and Supportive Care.