Barry James O'Sullivan (born 24 March 1957) is an Australian politician who was a senator for Queensland from 11 February 2014 until 30 June 2019. He is a member of the Liberal National Party of Queensland (LNP) and sat with the Nationals in federal parliament. A former police detective, grazier, property developer and LNP executive treasurer, O'Sullivan was appointed by the Queensland Parliament to the Senate seat vacated by Barnaby Joyce, who had resigned to contest the House of Representatives seat of New England at the 2013 federal election. He was elected to a three-year term at the 2016 federal election.