Six former 'Big Brother' participants, who face the daunting challenges of the Library in order to win money for Great Ormond Street Hospital. Former housemates who took part in the special were Spencer Smith from Big Brother 3, Big Brother 7 runner-up Glyn Wise, Big Brother 8 winner Brian Belo, Marcus Akin from Big Brother 10, Big Brother 11's Sam Pepper and Big Brother 11 winner Josie Gibson.
| Actor | Role |
|---|---|
 Zero KazamaSelf - Host | Self - Host |
| SSpencer SmithSelf - Housemate | Self - Housemate |
| GGlyn WiseSelf - Housemate | Self - Housemate |
 Brian BeloSelf - Housemate | Self - Housemate |
| MMarcus AkinSelf - Housemate | Self - Housemate |
| SSam PepperSelf - Housemate | Self - Housemate |
 Josie GibsonSelf - Housemate | Self - Housemate |