Half-Caste Act was the common name given to Acts of Parliament passed in the colony of Victoria (Aboriginal Protection Act 1886) and the colony of Western Australia (Aborigines Protection Act 1886) in 1886. They became the model for legislation to control Aboriginal people throughout Australia - Queensland's Aboriginals Protection and Restriction of the Sale of Opium Act 1897; NSW/ACT's Aboriginal Protection Act 1909; the Northern Territory Aboriginals Act 1910; South Australia's Aborigines Act 1911; and Tasmania's Cape Barren Island Reserve Act 1912.
The various related Acts allowed the seizure of "half-caste" children (i.e. mixed race children; a term now deemed offensive) and their forcible removal from their parents. This was theoretically to provide them with better homes than those afforded by typical Aboriginal people, where they could grow up to work as domestic servants, and also for social engineering. The removed children are now known as the Stolen Generations.
These Acts were a major impetus for a 1967 referendum question. Some of the controls first created by the Acts remained in place until the early 1970s.