William Williamson may refer to:

• William Williamson (American politician) (1875–1972), US Representative
• William Williamson (Australian politician) (1867–1950)
• William Crawford Williamson (1816–1895), English naturalist
• William D. Williamson (1779–1846), American, Governor of Maine, US Representative
• William Price Williamson (1884–1918), American officer in the U.S. Navy
• William Williamson (canoeist) (1915–1991), Canadian canoeist
• William Richard Williamson (1872–1958), English adventurer and oil company representative
• William Williamson (priest, born 1697) (1697–1765), Anglican priest in Ireland, Archdeacon of Kildare
• William Williamson (priest, born 1645) (1645–1722), Irish Anglican priest, Archdeacon of Glendalough
• Willie Williamson, college football coach
• Bill Williamson (1922–1979), Australian jockey
• Bill Williamson (footballer) (1887–1918), English footballer

• Billy Williamson (disambiguation)
• Williamson (surname)
• Williamson (disambiguation)