Mitchell Peter Fifield is an Australian politician and diplomat who last served as the Permanent Representative of Australia to the United Nations. He previously served as a Senator for Victoria from 2004 to 2019, representing the Liberal Party. He was a government minister in the Abbott, Turnbull, and Morrison governments, serving as Assistant Minister for Social Services (2013–2015), Manager of Government Business in the Senate (2013–2015), Minister for Communications (2015–2019), and Minister for the Arts (2015–2019).

The ambassador and permanent representative of Australia to the United Nations is an officer of the Australian Department of Foreign Affairs and Trade and the head of the Permanent Mission of the Commonwealth of Australia to the United Nations in New York. The position has the rank and status of an ambassador extraordinary and plenipotentiary and is the lead Australian representative to the UN, although that role is also shared with representatives present at the United Nations Office in Geneva, the United Nations Office in Vienna and the United Nations Office at Nairobi, and the delegations to UNESCO and the United Nations Agencies in Rome. Australia is a charter member of the United Nations and has sent representatives to New York since 1946.