Big Brother 2002, also known as Big Brother 3, was the third series of the British reality television series Big Brother. The show followed fourteen contestants, known as housemates, who were isolated from the outside world for an extended period of time in a custom built House. Each week, one or more of the housemates were evicted by a public vote. The last remaining housemate, Kate Lawler, was declared the winner, winning a cash prize of £70,000.

Big Brother is the British version of the international reality television franchise Big Brother created by producer John de Mol in 1997. Broadcast yearly from 18 July 2000 to 5 November 2018, and returned on 8 October 2023, the show follows the format of other national editions, in which a group of contestants, known as "housemates", live together in a specially constructed house that is isolated from the outside world. They are continuously monitored by live television cameras and personal audio microphones. Throughout the competition, housemates are "evicted" from the house by public televoting. The last remaining housemate wins the competition and a cash prize. The series takes its name from the oppressive character known by that name in George Orwell's 1949 novel Nineteen Eighty-Four.