Big Brother Australia is an Australian reality show based on the international Big Brother format created by John de Mol.

Big Brother is a reality competition television franchise created by John de Mol Jr., first broadcast in the Netherlands in 1999 and subsequently syndicated internationally. The show features contestants called "housemates" or "HouseGuests" who live together in a specially constructed house that is isolated from the outside world. The name is inspired by Big Brother from George Orwell's novel Nineteen Eighty-Four, and the housemates are continuously monitored during their stay in the house by live television cameras as well as personal audio microphones. Throughout the course of the competition, they are voted out until only one remains and wins the cash prize.