William Henry McMaster was an American politician who served as the tenth governor of South Dakota from 1921 until 1925. A member of the Republican Party, he went on to serve as a member of the United States Senate from South Dakota from 1925 to 1931.
- Occupation
- politician
- Position held
- member of the South Dakota House of Representatives, Governor of South Dakota, United States senator, United States senator
- Citizenship
- United States
- Born
- May 10, 1877
- Died
- September 14, 1968