John Tonkin, Australian politician, 20th Premier of Western Australia (died 1995)

John Trezise Tonkin was an Australian politician who was the premier of Western Australia from 3 March 1971 to 8 April 1974. A member of the Labor Party, Tonkin was a minister in the Willcock, Wise and Hawke governments. He was a member of the Western Australian Legislative Assembly from 1933 to 1977, making him the longest-serving member of the Parliament of Western Australia as of 2021.

The premier of Western Australia is the head of government of the state of Western Australia. The role of premier at a state level is similar to the role of the prime minister of Australia at a federal level. The premier leads the executive branch of the Government of Western Australia and is accountable to the Parliament of Western Australia. The premier is appointed by the governor of Western Australia. By convention, the governor appoints as premier whoever has the support of the majority of the Western Australian Legislative Assembly, the lower house of the Parliament of Western Australia. In practice, this means that the premier is the leader of the political party or group of parties with a majority of seats in the Legislative Assembly. Since Western Australia achieved self-governance in 1890, there have been 31 premiers. Roger Cook is the current premier, having been appointed to the position on 8 June 2023.