William Thornton (1759–1828) was an American physician, inventor, painter and architect.
William Thornton or Bill Thornton may also refer to:
- William Thornton (academic), principal of Hart Hall, later Hertford College, Oxford, 1688–1707
- William Thornton (died 1769) (died 1769), English militia officer and politician
- William Thornton (Virginia burgess) (1717–1790), Colonial Virginia planter and politician
- William Thornton (British Army officer) (1779–1840), British general
- William Thornton (Kansas politician), Kansas politician
- William E. Thornton (1929–2021), American astronaut
- William J. Thornton (1878–1951), American businessman and politician
- William L. Thornton (1844–1915), New York politician and judge
- William Neville John Thornton, Northern Irish politician
- William Patton Thornton (1817–1883), American physician
- William Taylor Thornton (1843–1916), governor of New Mexico Territory, 1893–1897
- William Wheeler Thornton (1851–1932), American jurist and author from Indiana
- Willie Thornton (1920–1991), Scottish footballer
- William Thornton (firefighter) (1826–1848), first firefighter to die on the job in Ontario
- Willie Thornton (Canadian football) (born 1986), Canadian football wide receiver
- Bill Thornton, mayor of San Antonio, Texas, 1995–1997
- Bill Thornton (American football) (1939–2008), American football fullback
- Billy Bob Thornton (born 1955), American actor
- Billy Thornton (rugby league), rugby league footballer of the 1940s for England, and Hunslet
- William Thornton (Queensland politician) (1817–1884), member of the Queensland Legislative Council
- William Thomas Thornton (1813–1880), economist, civil servant and author