Samuel Osiah Thier (born June 23, 1937) is professor of Medicine and Health Care Policy at Harvard University. He earned his medical degree at the State University of New York Upstate Medical University in 1960. He previously served as the president of Brandeis University from 1991–1994 and the president of the Massachusetts General Hospital from 1994-96. Thier is an authority on internal medicine and kidney disease and is also known for his expertise in national health policy, medical education and biomedical research.