William Porter may refer to:
- William Dennison Porter (1810–1883), South Carolina lieutenant governor
- William Porter (Attorney General) (1805–1880), attorney-general of the Cape Colony
- William Field Porter (1784–1869), New Zealand politician
- William G. Porter, American police officer
- William J. Porter (1914–1988), American diplomat; former ambassador to Canada and Saudi Arabia, among others
- William Archer Porter (1825–1890), British lawyer and educationist
- William Haldane Porter (1867–1944), British civil servant
- William Porter (died c. 1593), member (MP) of the Parliament of England for Grantham, Bletchingley, and Helston
- William Porter (fl. 1388), Member of Parliament (MP) for Southwark
- William Porter (died 1436), MP for Cambridgeshire
- William W. Porter (1856–1928), American attorney and legal author
- William Wood Porter (1826–1907), American military officer and jurist