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 (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 (born 1937), Scottish professional footballer 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., 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