Line of Duty is a British police procedural and serial drama created by Jed Mercurio and produced by World Productions for the British Broadcasting Corporation (BBC). It first began broadcasting on BBC Two on 26 June 2012. The programme performed well and was quickly commissioned for additional series that aired in 2014 and 2016. After becoming the highest-rated series on BBC Two in 10 years, Line of Duty was promoted to BBC One beginning with the fourth series in 2017 and fifth in 2019, securing commissions through a sixth series, which concluded on 2 May 2021, after the programme had aired a total of 36 episodes.

The series stars Martin Compston, Vicky McClure, and Adrian Dunbar, among others. It revolves around Anti-Corruption Unit 12 (AC-12), a team inside a fictional police force tasked with "policing the police". Mercurio originally pitched the series to BBC One in 2011 but was turned down and directed towards BBC Two. It ultimately transferred to BBC One after the two networks were restructured. Mercurio has written the entirety of the series, directing some episodes, as well as performing as producer and executive producer. Filming of the first series took place in Birmingham, England before moving to Belfast, Northern Ireland for the remainder of the programme. Simon Heath, Stephen Wright, and Tommy Bulfin are additional executive producers of the show which was also produced with Northern Ireland Screen and BBC Northern Ireland.

Line of Duty has secured an international cult following despite complications with international distribution rights. The series has been praised by many critics, although it received some criticism for its conclusion of a long story arc. It set viewership records and became the highest-rated drama in the UK since 2002. The programme has been the subject of several accolades including multiple nominations for British Academy Television Awards (BAFTA TV). Following the sixth series, the future of the programme has remained uncertain.