Big Brother 2000, also known as Big Brother 1, was the first series of the British reality television series Big Brother. It is based upon the Dutch series of the same name, which gained notoriety in 1999 and 2000. The series debuted on Channel 4 on 18 July 2000, running for nine weeks until 15 September 2000. Early in its run, the series was met with controversy for numerous reasons, including its use of professional psychiatrists who analyzed the personalities and actions of the contestants. Despite the large amount of controversy, the series was a major success. Forty thousand people applied to participate in the first series. The first week of the series had over 400,000 voters call in to choose to evict someone, while the final week had 7.8 million voters. The series averaged 4.5 million viewers, with a series high of 10 million viewers on the final night. This series featured a total of eleven housemates competing to win the grand prize. The show lasted for a total of 64 days, culminating in housemate Craig Phillips winning the grand prize, and Anna Nolan coming in second place.

The series revolves around ten strangers 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. Each week, each contestant, referred to as "housemates", chooses two people to be up for eviction. 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 £70,000 grand prize. A housemate can be ejected from the show for breaking rules, such as discussing nominations when not permitted. If a housemate were to be ejected from the game - as in the fifth week - then a replacement housemate would enter the House in a matter of days.