Big Brother 2012, also known as Big Brother 13, was the thirteenth series of the British reality television series Big Brother, and the second series to broadcast on Channel 5. The series premiered with a live launch on 5 June 2012 and ran for 70 days, concluding on 13 August 2012. The series was originally planned to run for thirteen weeks, but was cut back to ten weeks in order to accommodate Celebrity Big Brother 10. The series was won by Luke Anderson, who won half of the £100,000 prize fund, with the remainder taken by Conor McIntyre as part of the White Room twist. Anderson is the second transsexual contestant to win the show, the first being Nadia Almada who won the show back in 2004. The runner-up was Adam Kelly. The series was announced in April 2011 when Channel 5 signed a two-year contract to air the show. With Big Brother 12 having been broadcast in autumn 2011, this is the first series to air in the show's regular summer period on Channel 5 since it acquired the show from Channel 4 in 2011.

There were 16 original housemates, eight men and eight women, who all entered the house on Day 1. Shortly after the first eviction of the series, Becky Hannon, one of three wildcard housemates, was chosen by the public to enter the house on Day 4. For the first time since Big Brother 5, no housemate left the House voluntarily. The only housemate not to be evicted by a public vote was Conor, who left with half of the £100,000 prize fund as part of the White Room twist.