Samuel Proctor Massie, Jr. (July 3, 1919 – April 10, 2005) was a chemist who studied a variety of chemicals that contributed towards the development of therapeutic drugs, including the chemistry of phenothiazine. As one of the African American scientists and technicians on the Manhattan Project to develop atomic bombs in World War II Massie worked with uranium isotopes. Massie was named one of the top 75 distinguished contributors to chemistry in history by Chemical and Engineering News.