Onslow is a surname. Notable people with the surname include:
Sir Alexander Onslow (1842–1908), third Chief Justice of the Supreme Court of Western Australia Arthur Onslow (disambiguation) Cranley Onslow (1926–2001), British politician Denzil Onslow (disambiguation) Edward Onslow (1758–1829), British nobleman, Member of Parliament and fellow of the Royal Society George Onslow (disambiguation) Guildford Onslow (1814–1882), English politician Hannah Onslow (born 1998), English actress Jack Onslow (1888–1960), American Major League Baseball player, manager, coach and scout Muriel Wheldale Onslow (1880–1932), British biochemist Richard Onslow (disambiguation) Thomas Onslow (disambiguation) William Onslow, 4th Earl of Onslow (1853–1911) William Onslow, 6th Earl of Onslow (1913–1971)