Crimewatch (formerly Crimewatch UK) is a British television programme produced by the BBC, that reconstructs major unsolved crimes in order to gain information from the public which may assist in solving the case. The programme was originally broadcast once a month on BBC One, although in the final years before cancellation it was usually broadcast roughly once every two months.

Crimewatch was first broadcast on 7 June 1984, and is based on the German TV show Aktenzeichen XY… ungelöst (which translates as File Reference XY … Unsolved). Nick Ross and Sue Cook presented the show for the first eleven years, until Cook's departure in June 1995. Cook was replaced by Jill Dando. After Dando was murdered in April 1999, Ross hosted Crimewatch alone until January 2000, when Fiona Bruce joined the show.Kirsty Young and Matthew Amroliwala replaced Ross and Bruce following their departures in 2007. The BBC announced on 15 October 2008 that they would move production of shows such as Crimewatch to studios in Cardiff. Young and Amroliwala remained as the lead presenters until 2015. Following a brief period with guest presenter Sophie Raworth in 2016, it was announced that the show would relaunch in September 2016 with a new weekly format. The new presenters were announced as Jeremy Vine and Tina Daheley. The new series began on 5 September 2016, with the final episode broadcast on 20 March 2017.

In October 2017, the BBC announced that the main Crimewatch series had been cancelled, citing declining viewership. The daytime spin-off series Crimewatch Roadshow (now Crimewatch Live) would continue to air, but will also air more episodes per year. Crime NI, a similar live monthly programme in partnership with Crimestoppers UK, was aired from 3 September 2021 to 11 April 2022 on BBC One Northern Ireland and presented by Wendy Austin and Dearbhail McDonald.