William Westwood Lockyer is a retired American politician from California, who held elective office from 1973 to 2015, as State Treasurer of California, California Attorney General, and President Pro Tempore of the California State Senate.

The state treasurer of California is a constitutional officer in the executive branch of the government of the U.S. state of California. Thirty-five individuals have held the office of state treasurer since statehood. The incumbent is Fiona Ma, a Democrat. The state treasurer's main office is located in the Jesse M. Unruh State Office Building in Sacramento.