William Donald Schaefer was an American politician who served in public office for 50 years at both the state and local level in Maryland. As a Democrat, he was the 45th mayor of Baltimore from December 1971 to January 1987, the 58th Governor of Maryland from January 21, 1987, to January 18, 1995, and the 32nd Comptroller of Maryland from January 20, 1999, to January 17, 2007. On September 12, 2006, he was defeated in his reelection bid for a third term as Comptroller by Maryland Delegate Peter Franchot in the Democratic Party primary.

The comptroller of Maryland is a constitutional officer of the U.S. state of Maryland. Thirty-four individuals have held the office of comptroller since 1851, when the office was created. The incumbent is Brooke Lierman, a Democrat.