Celebrity Big Brother 15 was the fifteenth series of the British reality television series Celebrity Big Brother. The series launched on 7 January 2015 on Channel 5 and ended after 31 days on 6 February 2015; at the time it was the longest ever celebrity series. The seventeenth series in 2016 lasted a day longer with 32 days. It was the eighth celebrity series and the twelfth series of Big Brother overall to air on the channel. Emma Willis returned to host the series, whilst Rylan Clark continued to present the spin-off show Celebrity Big Brother's Bit on the Side alongside Willis. Repeats of the series aired on MTV, the first to do so. Willis decided to leave Big Brother's Bit on the Side after the end of this series, hosting her final show on 2 February 2015.