BBC Four is a British television channel operated by the British Broadcasting Corporation (BBC) and available to digital television viewers on Freeview, IPTV, satellite and cable.

BBC Four launched on 2 March 2002, transmitting a schedule between 19:00 to 4:00. It shows "a wide variety of programmes including drama, documentaries, music, international film, original programmes, comedy and current affairs ... an alternative to programmes on the mainstream TV channels." It has a schedule dominated by repeats but is required by its licence to broadcast at least 100 hours of new arts and music programmes, 110 hours of new factual programmes and premier 20 international films each year.

BBC Four launched on 2 March 2002 at 19.00 GMT, having been delayed from the original planned 2001 launch. The channel replaced BBC Knowledge, an educational and cultural channel which had undergone many changes throughout its lifetime; the latter of which consisted of documentaries and art programming: essentially a test of the new BBC Four schedule. BBC Four would rebrand this channel, and bring it into line with the well recognised BBC One and Two brands at the same time. Planning for the new channel, along with the new BBC Three, had been in progress since October 2000; however the incumbent government delayed approving the new BBC digital plans. The BBC Four plans were approved earlier, and as a result launched before BBC Three.