William Smyth (c. 1460–1514) was an English bishop.

William Smyth may also refer to:

• Sir William Smyth, 1st Baronet (c.1616–1696), English politician
• William Smyth (Irish politician), UK MP for the Irish constituency of Westmeath, 1801–1808
• William Smyth (congressman) (1824–1870), American politician
• William Smyth (Australian politician) (1846–1899), Australian politician for electoral district of Gympie
• William Ross Smyth (1857–1932), Canadian politician
• William James Smyth (1886–1950), labour member of the Senate of Northern Ireland

• Bill Smyth (umpire) (1916–2007), Australian cricket umpire
• Billy Smyth (1925–2005), Northern Irish footballer
• Bill Smyth (American football) (1922–1966), American football player

• William Smyth (English bishop) (1858-1950), better known as Edmund Smyth, Anglican bishop in England and South Africa
• William Smyth (Irish bishop) (1642–1705), Anglican bishop in Ireland
• William Blood Smyth, Archdeacon of Killaloe, 1927–1938
• William Smyth (priest, born 1683) (1683–1759), Dean of Ardfert and Archdeacon of Meath
• William Smyth (priest, born 1662) (1662-1710), Irish Anglican priest, Archdeacon of Connor

• William Smyth (architect) (died 1490), English Gothic architect
• William Smyth (academic administrator) (1582–1658), English academic administrator at the University of Oxford
• William Smyth (historian) (1765–1849), English historian
• William Henry Smyth (1788–1865), British astronomer and admiral
• William Smyth (professor) (1797–1868), American mathematician

• William Smythe (disambiguation)
• William Smith (disambiguation)