Darkest Hour is a 2017 British biographical war drama film directed by Joe Wright and written by Anthony McCarten. It stars Gary Oldman as Winston Churchill, in his early days as Prime Minister of the United Kingdom during the Second World War and the May 1940 war cabinet crisis. The cast also includes Kristin Scott Thomas as Clementine Churchill, Lily James as Elizabeth Layton, Stephen Dillane as Viscount Halifax, Ronald Pickup as Neville Chamberlain, and Ben Mendelsohn as King George VI. The title of the film refers to a phrase describing the early days of the war, widely attributed to Churchill.

Darkest Hour had its world premiere at the 44th Telluride Film Festival on 1 September 2017. It began a limited release in the US on 22 November 2017, followed by a wide release on 22 December, and was released on 12 January 2018 in the UK. The film grossed $150 million worldwide and received positive reviews from critics, who particularly lauded Oldman's performance and deemed it one of the best of his career. Darkest Hour received several accolades, including Best Actor for Oldman at the Academy Awards, the BAFTAs, the Golden Globes, and the SAG Awards.