William Knox may refer to:
Australia
William Dunn Knox (1880–1945), Australian artist William Knox (Victorian politician) (1850–1913), Australian politician - House William Knox (Queensland politician) (1927–2001), Australian state politician - Legislative Assembly
United Kingdom William Knox (official) (1732–1810), Irish colonial under-secretary in Great Britain and pamphleteer William Knox (Scottish poet) (1789–1825), Scottish poet and journalist William Knox D'Arcy (1849–1917), British entrepreneur William Knox (footballer, fl. 1927–1934), Scottish professional footballer William Knox (footballer, born 1904), Scottish professional footballer William Knox (MP) (1826–1900), MP for Dungannon William Knox (British Army officer) (1847–1916), British general William Knox (bishop) (1762–1831), Bishop of Killaloe and Kilfenora William Knox (artist) (1862–1935), British artist of marine paintings and scenes of Venice William Knox (cricketer) (1903–1954), Scottish cricketer Bill Knox (1928–1999), Scottish author Willie Knox (1937–2026), Scottish professional football player and manager
United States Frank Knox (William Franklin Knox, 1874–1944), American Secretary of the Navy William F. Knox (1885–1975), American football player and coach and lawyer William Jacob Knox Jr. (1904–1995), African-American chemist, worked on the Manhattan Project William J. Knox (1820–1867), California businessman and politician William Shadrach Knox (1843–1914), American congressman from Massachusetts William W. Knox (1911–1981), U.S. federal judge