The Australian monarchy is hereditary and constitutional. The incumbent, since 6 February 1952, is Elizabeth II who reigns as Queen of Australia. The heir apparent is Elizabeth's eldest son, Prince Charles.

At the federal level, royal power within the Commonwealth of Australia is exercised by a Governor-General in accordance with the Australian Constitution and Letters Patentblank">http://www.gg.gov.au/governorgeneral/content.php?id=4http://www.gg.gov.au/governorgeneral/content.php?id=3 from the Queen. Save for a few specific constitutional duties such as appointing and terminating the commission of the Governor-General, the sovereign does not exercise these powers in person. Additionally there are certain ceremonial functions, such as the opening of Parliament or the conferral of honours which, while usually performed by the Governor-General, may be performed in person by the sovereign. Because the majority of the sovereign's powers are exercised both de jure and de facto by the Governor-General and not by the sovereign personally, there is some debate as to whether the sovereign or the Governor-General is Australia's "head of state". In each of the _states, the monarch's powers are exercised by a Governor appointed directly by the Queen on the advice of the respective State government. When personally present in an Australian state, however, the monarch may herself perform any of the State Governor's functions. In contradistinction to the states, Australian territories do not have Governors appointed directly by the monarch; instead the Crown is represented either directly by the Governor-General of the Commonwealth or indirectly by an Administrator appointed by the Governor-General.

The Australian monarch, besides reigning in Australia, separately serves as monarch for each of fifteen other Commonwealth countries known as Commonwealth realms. This developed from the former colonial relationship of these countries to Britain, but they are now independent and the monarchy of each is legally distinct.