2017–2022: Doctor Who
On 16 July 2017, the BBC announced Whittaker would play the Thirteenth Doctor in the science fiction television series Doctor Who; she is the first woman to play the Doctor. She had previously worked with incoming Doctor Who showrunner Chris Chibnall on Broadchurch. She admitted that she had to "tell a lot of lies" after being cast to keep the information secret and used the codeword "Clooney" when talking about the role. Whittaker kept her mother in "the inner circle" regarding knowledge of the role, as her father, Adrian, "would have the ability to tell the world".
She urged fans not to be afraid of her gender, saying "Doctor Who represents everything that's exciting about change. The fans have lived through so many changes, and this is only a new, different one, not a fearful one." Chibnall said that he always wanted a woman for the part and that Whittaker was their first choice.
Reaction to Whittaker's casting was mostly positive, although a "sizeable minority" was unhappy. Some said that a female Doctor would be a good role model for young girls, while others felt the Doctor was only ever meant to be male, or criticised the casting as an exercise in political correctness.
Whittaker debuted in the 2017 Christmas special "Twice Upon a Time" while her opening episode The Woman Who Fell to Earth is the highest-viewed premiere episode of a debuting Doctor in the show's history with 10.96 million viewers.
In November 2018, the BBC confirmed that the twelfth series, Whittaker's second series, had begun production. Whittaker returned for the thirteenth series, and also voiced the Doctor in the 2022 BBC Sounds podcast Doctor Who: Redacted. She departed the programme following the series and three associated specials in 2022. Whittaker generally received praise for her performance. Though some felt the Thirteenth Doctor did little to combat social and political injustices, others felt the era's storylines were too 'politically correct', criticising what they saw as the show taking a more socially progressive outlook during Whittaker's tenure.
On May 31, 2025, Whittaker made a surprise cameo, reprising her role as the Thirteenth Doctor in the Doctor Who series 15 finale "The Reality War", alongside Ncuti Gatwa as the Fifteenth Doctor. Starting in July 2025, Whittaker reprised her role as the Thirteenth Doctor in a series of Doctor Who audio dramas from Big Finish Productions.
