Celebrity Big Brother 2001, also known as Celebrity Big Brother 1, was the first series of Celebrity Big Brother. In aid of the British charity Comic Relief, six celebrities entered the Big Brother 1 house for eight days. The series premiered on March 9, 2001 and concluded on March 16, 2001. While Channel 4 aired daily highlights shows, BBC One also aired 10-minute updates. Along with these updates, they also aired the finale, which was part of the Red Nose Day telethon. Celebrity Big Brother 1 was the first Big Brother series to feature a live launch, something which is now common for every season of the series. Initially meant to be a one-time series, the success of Celebrity Big Brother 1 later influenced the decision to make Celebrity Big Brother an annual occurrence, much like the main series. To date, twelve seasons have aired.
The premise of the series remained similar to that of the main series. The series revolves around six celebrities living in a house together with no communication with the outside world. They are filmed constantly during their time in the house, and can have no communication with those filming them. Every other day in the game, each contestant, referred to as "housemates", choose two people to be up for nomination. The two or more people with the most votes will be nominated to leave the house. The viewers then decide which of the nominees should leave, with the selected person leaving during a live show. This process continued until only three housemates remained, in which the viewers would decide which of the housemates would win the series. Whereas the winner of the main series receives a cash prize, the celebrity edition of the series sees them competing for charity. A housemate can be ejected from the show for breaking rules, such as discussing nominations when not permitted.