William George Hayden (23 January 1933 – 21 October 2023) was an Australian politician who served as the 21st governor-general of Australia from 1989 to 1996. He was Leader of the Labor Party and Leader of the Opposition from 1977 to 1983, and served as Minister for Foreign Affairs and Trade from 1983 to 1988 under Bob Hawke and as Treasurer of Australia in 1975 under Gough Whitlam.
Hayden was born in Brisbane, Queensland. He attended Brisbane State High School and then joined the Queensland Police, working as a police officer for eight years while studying economics part-time at the University of Queensland. Hayden was elected to the House of Representatives at the 1961 federal election, aged 28 – along with Manfred Cross and Doug McClelland, Hayden was the earliest elected Labor MP still alive at the time of his death. When Gough Whitlam led the Labor Party to victory in 1972, Hayden was made Minister for Social Security. He replaced Jim Cairns as treasurer in 1975, but served for only five months before the government was dismissed.