William or Billy Pratt may refer to:
William B. Pratt (1935–2019), American physician and politician William Pratt (MP for Southwark), English politician William Henry Pratt, real name of actor Boris Karloff William Pratt (born 1609), ancestor of the Pratt-Romney family Billy Pratt (rugby league) (1932–2009), English rugby league footballer of the 1950s for Leeds, and Halifax
William V. Pratt (1869–1957), admiral in the United States Navy USS William V. Pratt, a Farragut-class destroyer in the service of the United States Navy William W. Pratt (c. 1821 – 1864), American playwright and actor William Pratt (priest) (1732–1770), Anglican priest in Ireland William Pratt (cricketer) (1895–1974), English cricketer William Dymock Pratt (1854–1916), English architect William Pratt (businessman) (1928–1999), Canadian businessman Billy Pratt (footballer, born 1872) (1872–?), English football winger for Small Heath from 1889 to 1892 Billy Pratt (footballer, born 1874) (1874–?), English football full-back for Small Heath from 1894 to 1902 Spike (Buffy the Vampire Slayer), a character from television series Buffy the Vampire Slayer