Charles William Duncan, Jr. (born September 9, 1926) is an American entrepreneur, administrator, and statesman best known for serving as U.S. Secretary of Energy on the Cabinet of President Jimmy Carter from 1979 to 1981. He had previously served as Carter's United States Deputy Secretary of Defense during the Iranian Revolution. Earlier, Duncan had run the family business, Duncan Coffee Company of Houston, Texas, for seven years, until the Coca-Cola Company acquired it in 1964.