David Ean Leyonhjelm ( "lion-helm"; born 1 April 1952) is an Australian former politician. He was a Senator for New South Wales, representing the Liberal Democratic Party from 2014 to 2019. Having been elected at the 2013 federal election, he took office on 1 July 2014, and was re-elected in the 2016 full Senate election. He resigned from the Senate in March 2019 to stand for the Legislative Council at the 2019 New South Wales state election, but failed to be elected. Before being elected to federal parliament, Leyonhjelm worked as a veterinarian and then as an agribusiness consultant. He also writes columns for several Australian publications, with a concentration on rural issues.