William, Willie, Bill, or Billy Horne may refer to:
Politics William Horne (British politician) (1774–1860) British member of parliament and Attorney General for England and Wales Bill Horne (born 1948), Canadian politician William C. Horne (b. 1962), Nevada state representative William S. Horne (1936–2022), Maryland politician and judge
Sports William Horne (golfer) (born 1880), English golfer William Horne (footballer) (1885–1930), English football player Billy Horne (1916–1969), American baseball player Willie Horne (1922–2001), English rugby league player
Others Brother William Horne (d. 1540), one of the "Carthusian Martyrs" William Kenneth Horne (1883–1959), British colonial judge and speaker William Horne (tenor) (1913–1983), operatic tenor, notably with the New York City Opera
See also William Horn (1841–1922), Australian mining magnate, pastoralist, politician, author, sculptor and philanthropist Will Horn, American baseball player of the 1900s Bill Horn (born 1967), Canadian ice hockey player and coach Billy Horn (born 1938), Scottish footballer Sir William Whorne, Lord Mayor of London in 1487