The thirteenth series of the British science fiction television programme Doctor Who, known collectively as Flux, was broadcast from 31 October to 5 December 2021. The series is the third and last to be led by Chris Chibnall as head writer and executive producer. It is the thirteenth to air following the programme's revival in 2005, and the thirty-ninth season overall. The series, initially announced in November 2019, was broadcast on Sunday nights, and will be followed by three associated specials which are set to air in 2022.