Big Brother: Celebrity Hijack was a special series of Celebrity Big Brother, a spin-off series of the British reality television programme Big Brother. It was broadcast on E4 from 3 January - 28 January 2008. A number of closely associated programmes also aired on the same channel. Dermot O'Leary - who had hosted Big Brother's Little Brother since 2001 - was the main host of Celebrity Hijack, and it was his final series of Big Brother.

The series was announced on 8 October 2007 by Channel 4 and that it would be replacing Celebrity Big Brother in January 2008, due to the widely publicised racism controversy in Celebrity Big Brother 5. In 2009, Celebrity Big Brother returned to Channel 4 and no further series' of Celebrity Hijack were produced.

The premise of the series saw one celebrity a day taking control, with the help of Big Brother; organising their own tasks, making their own rules and talking to the housemates in the Diary Room. They were in charge of a set of housemates, ranging in age from 18–21 years old and all having a special talent.

The housemates competed to be the last to leave the house for a £50,000 prize. The series ended on 28 January where John Loughton was voted as the winner.