William Day may refer to:
- William H. Day (1825–1900), U.S. Black abolitionist
- William Day (bishop) (1529–1596), English clergyman
- William Day (divine) (died 1684), English clergyman
- William Day (sea captain) (1715–1797), Massachusetts naval captain during the American Revolutionary War
- William Day (architect), Irish architect from County Wexford
- William Day (horseman) (1823–1908), British racehorse trainer
- William Day (lithographer) (1797–1845), British lithographer and watercolour artist
- William Day (Australian politician) (fl. 1861), member of the New South Wales Legislative Council
- William J. Day (1876–1950), judge from Massachusetts
- William Louis Day (1876–1936), American judge
- William Peyton Day (1886–1966), architect and co-founder of architectural firm Weeks and Day with Charles Peter Weeks
- William R. Day (1849–1923), American diplomat and Supreme Court Justice
- William S. Day (1923–1984), American politician in the state of Washington
- Will Day, former chair of the UK Sustainable Development Commission
- Will Day (born 2001), Australian rules footballer
- Bill Day (cartoonist), American cartoonist
- Bill Day (baseball) (1867–1923), Major League Baseball player
- Bill Day (politician), Virginia
- Bill Day (alpine skier) (1934–2024), Australian Olympic skier
- Bill Day (filmmaker), American documentary filmmaker
Topics referred to by the same termThis disambiguation page lists articles about people with the same name. If an internal link led you here, you may wish to change the link to point directly to the intended article. Category: