Unforgotten is a British crime drama television series, which initially aired on ITV on 8 October 2015. It was created and written by Chris Lang and directed by Andy Wilson. The programme follows a team of London detectives led by DCI Cassie Stuart (Nicola Walker) (Series 1–4), DCI Jessie James (Sinéad Keenan) (Series 5) and DI Sunny Khan (Sanjeev Bhaskar) as they solve cold cases of disappearance and murder.

Each series consists of six episodes. Series 1 to 4 were broadcast in the UK in 2015, 2017, 2018 and 2021. On 30 March 2021 a fifth series was announced, scheduled for release in 2023, and it was confirmed that Sanjeev Bhaskar would reprise his role. A year later it was confirmed that Sinéad Keenan would replace Walker as Bhaskar's new partner, DCI Jessica "Jessie" James. Filming for the fifth series began on 14 March 2022. The first episode of series 5 premiered on ITV in February 2023. In April 2023, ITV renewed the crime drama for a sixth series and it is scheduled to air in 2024.

Each series deals with a new case, introducing seemingly unconnected characters who are gradually revealed to have some relationship with the victim. As the murder mystery unfolds, the emotional ramifications of the crime on the lives of those affected are also explored.

Unforgotten has received critical acclaim. Tom Courtenay won the 2016 BAFTA TV Award for Best Supporting Actor for the first series and Mark Bonnar won the 2017 BAFTA Scotland for Best Actor in Television for the second series.