William Post may refer to:
(1857–1921), American photographer William Post Jr. (1901–1989), American actor and drama instructor William Post (polo player) (1911–1965), American polo player William Post (businessman) (1927–2024), American food manufacturer, inventor of Pop-Tarts William Post (lottery winner) (1939–2006), American lottery winner
See also Bill Post, American politician and radio personality in Oregon William Post Mansion, Buckhannon, West Virginia