William Thornton (1759–1828) was an American physician, inventor, painter and architect.
William, Willie, Bill, or Billy Thornton may also refer to:
Law and politics William Thornton (died 1769) (died 1769), English politician William Thornton (Virginia burgess) (1717–1790), British American colonial jurist William Thornton (Queensland politician) (1817–1884), Irish politician in Australia William Taylor Thornton (1843–1916), governor of New Mexico Territory William L. Thornton (1844–1915), American politician and judge in New York William Wheeler Thornton (1851–1932), American jurist and author in Indiana William J. Thornton (1878–1951), American politician in Illinois Neville Thornton (William Neville John Thornton) (born 1939/1940), Northern Irish politician Bill Thornton, American politician in Texas William Thornton (Kansas politician), American politician in Kansas
Sports Billy Thornton (rugby league) (fl. 1920s–1940s), English rugby league footballer Willie Thornton (1920–1991), Scottish footballer Bill Thornton (American football) (1939–2008), American football fullback Willie Thornton (Canadian football) (born 1986), Canadian football wide receiver
Others William Thornton (academic) (died 1707), English academic William Thornton (British Army officer) (1779–1840), British general William Thomas Thornton (1813–1880), English economist Sydney Jim (William Thornton, 1816–1858), English-born convict in Australia William Patton Thornton (1817–1883), American physician William Thornton (firefighter) (1826–1848), Canadian firefighter William E. Thornton (1929–2021), American astronaut Billy Bob Thornton (born 1955), American actor