William Mason, American surgeon and politician (d. 1860)
William Mason may refer to:

William Mason (gunsmith) (1837–1913), American engineer and inventor working for Remington, Colt, and Winchester

William Mason (composer) (1829–1908), American composer and pianist

William Mason (locomotive builder) (1808–1883), built locomotives at his Mason Machine Works between 1853 and 1889, including:

William Mason (locomotive), steam locomotive built by the aforementioned builder for the Baltimore and Ohio Railroad and later named in his honor

William Mason (architect) (1810–1897), architect and first mayor of Dunedin, New Zealand

William Mason (stenographer) (fl. 1672–1709), English writing-master

William Mason (poet) (1724–1797), English poet, editor and gardener

William Mason (religious writer) (1719–1791), Calvinist author and editor of the Gospel Magazine

William Mason (New York politician) (1786–1860), United States Representative from New York

William D. Mason (born 1959), prosecutor from Cuyahoga County, Ohio

William E. Mason (American politician) (1850–1921), U.S. Representative and Senator from Illinois

William E. Mason (Canadian politician) (1866–1951), former mayor of Regina, Saskatchewan, Canada

William E. Mason (East St. Louis mayor), former mayor of East Saint Louis, Illinois

William Mason (1757–1818), American militiaman in the American Revolutionary War and Virginia planter

William Temple Thomson Mason (1782–1862), Virginia farmer, businessman and politician

William Mason, 1st Baron Blackford (1862–1947), British politician and public servant

William Shaw Mason (1774–1853), statistician and bibliographer

William Mason (cricketer) (1811–1865), English cricketer

William Pinckney Mason (1843–1922), lieutenant in the Confederate States Navy

William S. Mason (1832–1899), mayor of Portland, Oregon, 1891–1894 and 1898–1899

William H. Mason, inventor of masonite

William Mason (1760–1830), Revolutionary War soldier, founder of city of Mason, Ohio

Todd Mason (William Todd Mason, born 1963), American entrepreneur

Bill Mason (1929–1988), Canadian canoeist and author

William Mason, a pseudonym of William W. Johnstone

Willie Mason (born 1980), Australian rugby league footballer

Willy Mason (born 1984), singer-songwriter

William Mason (Downton Abbey), a fictional character on the series Downton Abbey, played by Thomas Howes

William Mason, director of the Lyric Opera of Chicago