Oscar Douglas Hillgaar (born 8 November 1945) is a Norwegian politician formerly representing the Progress Party. He was born in Holt, and is of Irish descent. He attended the Norwegian Naval Academy from 1966 to 1967, and served in the Royal Norwegian Navy in Tromsø from 1967 to 1968. He worked as an air traffic controller assistant at Lakselv Airport, Banak from 1968 to 1969, then took air traffic controller education from 1969 to 1971. After completing his education he worked at Bodø, Bardufoss, Karmøy and Fornebu until 1989.