William S. Sly (October 19, 1932 – ) is an internationally known physician/scientist who, except for sabbatical years at Oxford and Stanford, spent his entire academic career in St. Louis. Following M.D. training at Saint Louis University School of Medicine, he trained in Internal Medicine at Washington University in St. Louis and in research laboratories at the NIH, in Paris, and in Madison, Wisconsin. He then joined the faculty at Washington University, where he directed the Division of Medical Genetics for 20 years. In 1984, he was recruited to St. Louis University School of Medicine and appointed Alice A. Doisy Professor and Chairman of the Edward A. Doisy Department of Biochemistry and Molecular Biology. He chaired that Department for 26 years. In February 2007, he was also named the