Prime Minister of Australia prime minister, otherwise William McMahon63. Robert Menzies was the oldest person to ever be prime minister, leaving office at 71 years old. The longest-serving Prime Minister was Sir Robert Menzies, who served in office twice: from 26 April 1939 to 28 August 1941, and again from 19 December 1949 to 26 January 1966. In total Robert Menzies spent 18 years, 5 months and 12 days in office. He served under the United Australia Party and the Liberal Party respectively. The shortest-serving Prime Minister was Frank Forde, who was appointed to the position on 6 July 1945 after the death of
Prime Minister of Serbia post-War Serbia, which took place on 9 April 1945. Governments were headed by President of the Government until 3 February 1953, President of the Executive Council until 15 January 1991 and again President of the Government since then, but the term Prime Minister is colloquially used (especially in the media) since the government of Dragutin Zelenović in 1991. In some later articles about the recent history of Serbia, term is retroactively applied to Stanko Radmilović, Desimir Jevtić and even back to Ivan Stambolić's government. Prime Minister of Serbia The Prime Minister of Serbia ( / "Premijer Srbije"), officially the President