The Principality of Hutt River, often referred to by its former name, the Hutt River Province, was an unrecognized micronation in Australia, proclaimed on 21 April 1970 when farmer Leonard Casley declared his farm to be a sovereign state, the "Hutt River Province". He claimed to have seceded from Australia, which occurred during his dispute with the authorities concerning wheat production quotas. A few years later, Casley began styling himself as "Prince Leonard" and granting family members royal titles, although he did not include the word "principality" in the official name until 2006. In 2017, Casley's claim to rulership was taken over by his son Graeme, who dropped the claim to sovereignty on 3 August 2020.

A micronation is a political entity whose representatives claim that they belong to an independent nation or sovereign state, but which lacks legal recognition by any sovereign state. Micronations are classified separately from de facto states and quasi-states; they are also not considered to be autonomous or self-governing as they lack the legal basis in international law for their existence. The activities of micronations are almost always trivial enough to be ignored rather than disputed by the established nations whose territory they claim—referred to in micronationalism as macronations. Several micronations have issued coins, flags, postage stamps, passports, medals and other state-related items, some as a source of revenue. Motivations for the creation of micronations include theoretical experimentation, political protest, artistic expression, personal entertainment and the conduct of criminal activity. The study of micronationalism is known as micropatriology or micropatrology.