Anglo-Celtic Australians, also known as British and Irish Australians, Colonial Stock Australians, or British Australians, and in colonial times as native white Australians, are a predominantly English-speaking ancestral group of Australians whose ancestors originate wholly or partially in the British Isles – predominantly in England (including Cornwall), Ireland, Scotland and Wales, as well as the Isle of Man, Channel Islands and British Isles descendent people of other settler colonies such as New Zealand, Canada, and historically, British Africa. The overwhelming majority of British Australians are descended from convicts and other early colonists; South Australia is the only state not founded as a British penal colony.

While Anglo-Celtic Australians do not form an official ethnic grouping in the Australian Bureau of Statistics' Australian Standard Classification of Cultural and Ethnic Groups, due to the long historical dominance and intermixture of Australians with ancestries from the British Isles, it is commonly used as an informal ethnic identifier.

The term has received criticism for erasing historical distinctions between English and Celtic settlers. In particular, it does not account for the political and social segregation of English and Irish Australians which some scholars have labelled an apartheid or the fact that while many English arrived in Australia as willing immigrants, many Irish were forcibly transported as prisoners or arrived as refugees.

At the 2021 census, the number of ancestry responses from the following groups as a proportion of the total Australian population amounted to 51.7%: English Australian, Irish Australian, Scottish Australian, Welsh Australian, Cornish Australians, British Australian (so described), Manx Australian, Channel Islander Australian. The precise number of Anglo-Celtic Australians is unknown due to the way in which ancestry data is collected in Australia. For instance, many census recipients nominated two Anglo-Celtic ancestries due to the long history of these ancestries in Australia, tending towards an overcount. Conversely, the Australian Bureau of Statistics has stated that most people nominating "Australian" ancestry have at least partial Anglo-Celtic European ancestry despite "Australian" ancestry being classified as part of the Oceanian ancestry group, tending towards an undercount.

The British Government initiated European settlement of the Australian continent by establishing a penal settlement at Sydney Cove in 1788. Between then and 1852, about 100,000 convicts (mostly tried in England) were transported to eastern Australia. Scotland and Wales contributed relatively few convicts.^{[citation needed]}

Native-born Australians of British and Irish descent were approximately a quarter of the population of the colony of New South Wales in both 1817 and 1828. There were slightly more native-born than free settlers in 1850. They were nearly half of the population in 1868. Their proportion of the population decreased during the times of the rapid population growth brought on by the goldrushes. The convicts were augmented by free settlers, including large numbers who arrived during the gold-rush in the 1850s. As late as 1861, people born in England, Wales, Scotland and Ireland outnumbered even the Australia-born population. The number of settlers in Australia who were born in the United Kingdom (UK) peaked at 825,000 in 1891, from which point the proportion of British among all immigrants to Australia steadily declined.

Until 1859, 2.2 million (73%) of the free settlers who immigrated were British.

From the beginning of the colonial era until the mid-20th century, the vast majority of settlers to Australia were from Britain and Ireland, with the English being the dominant group, followed by the Irish and Scottish. Among the leading ancestries, increases in Australian, Irish, and German ancestries and decreases in English, Scottish, and Welsh ancestries appear to reflect such shifts in perception or reporting. These reporting shifts at least partly resulted from changes in the design of the census question, in particular the introduction of a tick box format in 2001.