What was the name of the Australian Prime Minister who disappeared and is assumed to have died in office?

Harold Edward Holt (5 August 1908 – 17 December 1967) was born in Sydney, Australia and moved to Melbourne in childhood, studying law at the University of Melbourne. He was first elected to the Australian House of Representatives at the age of 27 in 1935.

Holt became Prime Minister of Australia in January 1966, elected unopposed as Liberal leader following the retirement of Robert Menzies. He fought a general election later that year, winning a landslide victory. The Holt government continued the dismantling of the White Australia policy, amended the constitution to give the federal government responsibility for indigenous affairs, and took Australia out of the sterling area. Holt promoted greater engagement with Asia and the Pacific, and made visits to a number of East Asian countries. His government expanded Australia's involvement in the Vietnam War, and maintained close ties with the United States under President Lyndon B. Johnson. The picture shows Holt (second from left) with other world leaders at the Southeast Asia Treaty Organization summit in Manila in October 1966.

Holt loved the ocean and had holiday homes at Portsea, Victoria, and Bingil Bay, Queensland. On 17 December 1967, while Holt was spending the weekend at Portsea, Holt disappeared while swimming in rough conditions at Cheviot Beach. He was presumed dead, although his body was never recovered; his disappearance spawned several conspiracy theories.