Light appeared as Henry Lennox in the BBC production North and South from the novel by Elizabeth Gaskell. He played the title character in the original National Theatre production of David Haig's My Boy Jack. An early screen role came in Cider with Rosie. He portrayed British pilot Robert Newman in the German film Dresden, in which he spoke German; and played Geoffrey, Duke of Brittany in the 2003 film The Lion in Winter alongside Patrick Stewart, Glenn Close and Jonathan Rhys-Meyers. He played Satan in two films released in 2005 which were titled ' and '. He also appeared in the title role of the 2009 play . In 2011, he appeared in an episode of BBC TV series Silk as Alan Bradley, a man accused of rape. In 2013, he appeared as Chief Inspector Roger Nelson in the BBC TV series WPC 56, and he appeared as Hercule Flambeau, nemesis of Father Brown, in the BBC TV series Father Brown episode 1.10 The Blue Cross. He reprised the role in the 2014 episode 2.5 The Mysteries of the Rosary, the 2015 episode 3.10 The Judgment of Man, the 2016 episode 4.5 The Daughter of Autolycus, the 2017 episode 5.15, "The Penitent Man", the 2018 episode 6.10 "The Two Deaths of Hercule Flambeau", the 2019 episode 7.10 "The Honourable Thief” and the 2020 episode 8.5 "The Folly Of Jephthah". Has appeared as Professor Felix Garwood in Lewis and in the prequel Endeavour. In 2016, he appeared as Dacourt in the ITV series Maigret episode 1.2 "Maigret's Dead Man". Light is a prolific stage actor. His theatre performances include the Complete Works Festival in Stratford-upon-Avon, where he starred in Sean Holmes' Julius Caesar as Brutus and in Rupert Goold's The Tempest as Caliban. In 2012, he appeared as the titular character in Thom Pain , a role for which critics praised him. In 2015, Light starred in the play Taken at Midnight with Penelope Wilton. He received a nomination for an Olivier for Best Supporting Actor in a Play. Soon after he starred as Escamillo in Carmen Disrupted with Sharon Stone. In late 2016 through early 2017, he was in a limited run of Mary Stuart along with Juliet Stevenson and Lia Williams at the Almeida. He continued the role after the play transferred to the West End's Duke of York's Theatre in 2018. In January 2019, it was announced that John Light would join the cast of Florian Zeller's "The Son." The play ran at the Kiln Theatre from February 20, 2019 through April 6, 2019. He will reprise the role in the West End production, scheduled to run in Fall 2019 at the Duke of York's Theatre. Light joined the cast of "Uncle Vanya" at the Theatre Royal Bath for a limited run in summer 2019. The production marked the directorial debut of Rupert Everett. During rehearsals, Everett accidentally injured Light's eye, which later led to Light falling off stage. Light performed using a crutch.
