Lux (Doctor Who)

"Lux" is the second episode of the fifteenth series of the British science-fiction television series Doctor Who. It was written by Russell T Davies, the Doctor Who showrunner, from a concept first developed over two decades prior, and directed by Amanda Brotchie. In the episode, the Fifteenth Doctor (Ncuti Gatwa) and his companion, Belinda Chandra (Varada Sethu), land in 1952 Miami, Florida, while trying to make their way back to 2025. After doing so, they discover a mysterious cinema where fifteen people have disappeared. The pair stay to investigate and ultimately confront an animated god, Lux (voiced by Alan Cumming), who traps them in film.

"Lux" is unusual for the programme in that it features a mixed live-action and animated format. Filming for the episode took place in Penarth, Cardiff and at Wolf Studios Wales in January 2024. Some voice-over work took place internationally in New York City in June. Animation and other post-production work continued later into the year, with some tasks still being completed as late as September.

The episode includes references to popular culture, fourth wall breaks and meta-references to its own fan base. It was released on BBC iPlayer, BBC One, and Disney+ on 19 April 2025. Reception to the episode was positive, with critics praising its use of animation in a live-action setting. Although "Lux" was noted for record low broadcast ratings, it received consolidated figures of 3 million. A novelisation written by James Goss is set to be released in July 2025.