William Marchant may refer to:
William Marchant (playwright) (1923–1995), American playwright and screenwriter William Sydney Marchant (1894–1953), British colonial administrator William Marchant (loyalist) (1948–1987), Northern Irish loyalist and volunteer in the Ulster Volunteer Force William Lavington Marchant (1828-1888), An Australian Pastoralist William Marchant (Rhode Island) (fl. 1800s), a Justice of the Rhode Island Supreme Court from 1808 to 1810