William Halsey Jr. (1882–1959), U.S. Naval officer and the commander of the United States Third Fleet during part of the Pacific War against Japan.
William Halsey may also refer to:
William F. Halsey Sr. (1853–1920), his father, U.S. naval officer William Darrach Halsey, American encyclopaedist and lexicographer William Melton Halsey (1915–1999), American abstract artist William Halsey (mayor) (1770–1843), mayor of Newark, New Jersey, 1836–1837 William Halsey (judge), Irish politician, soldier and judge
See also William Halsey Wood (1855–1897), American architect Admiral William Halsey Leadership Academy, a public high school in Elizabeth, New Jersey