On 16 July 2017, Whittaker was announced as the Thirteenth Doctor in the science fiction television series Doctor Who; she is the first woman to play the title role. 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. 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".
In November 2018, BBC confirmed that the twelfth series, Whittaker's second series, began production in November 2018. The series is set to air in early 2020.