William Saul Kroger (April 14, 1906 – December 4, 1995) was an American medical doctor who pioneered the use of hypnosis in medicine and was co-founder and founder of medical societies and academies dedicated to furthering psychosomatic medicine and medical hypnosis. Though he was trained as a gynecologist/obstetrician, his contributions to the medical field cut across disciplines and specialties in the medical field, including psychiatry, psychosomatic illness and treatment, endocrinology, neurobiology and bioengineering as well as his own specialty of gynecology and obstetrics.