William Jack is the name of:
William Jack (athlete) (born 1930), British Olympic sprinter William Jack (American politician) (1788–1852), member of the U.S. House of Representatives William Jack (Australian politician) (1892–1982) William Jack (botanist) (1795–1822), of Scotland William Jack (mathematician) (1834–1924), from Scotland William Brydone Jack (1817–1886), Canadian mathematician and astronomer