Portal:Australia/Anniversaries/April/April 21
- 1861 – On the Burke and Wills expedition, Burke, Wills, and King return to their base camp at Cooper Creek, having crossed the Australian continent from Melbourne to the Gulf of Carpentaria.
- 1883 – George Ernest Morrison arrives in Melbourne, Victoria, having walked 3,270 kilometres (2,030 mi) from Normanton, Queensland.
- 1970 – The Hutt River Province, a 75-square-kilometre (29-square-mile) property outside Northampton, Western Australia, declares its independence from Australia in response to new wheat production quotas, becoming Australia's first micronation.
- 1973 – Sir Arthur Fadden (pictured), the 13th Prime Minister of Australia, dies in Brisbane at the age of 79.
- 1976 – A gang of six men steal between A$6 million and 12 million from the Victoria Club, located in Queen Street, Melbourne.
- 1995 – Sir Gerard Brennan is appointed to the position of Chief Justice of Australia, succeeding Sir Harry Gibbs.