Kate Lethbridge-Stewart

Kate Lethbridge-Stewart, formerly known as Kate Stewart, is a fictional character in the British science fiction television series Doctor Who and its spin-off series, The War Between the Land and the Sea. She was created by writer Marc Platt and first portrayed by Beverley Cressman in the independent direct-to-video spin-offs Downtime (1995) and Dæmos Rising (2004). The character was reintroduced in the revived series by Chris Chibnall in the 2012 episode "The Power of Three," portrayed by Jemma Redgrave, who has continued in the role since then. Redgrave subsequently reprised her role as a lead character in the spin-off series The War Between the Land and the Sea in 2025.

Kate is the daughter of Brigadier Lethbridge-Stewart, a key figure from the classic series. Within the narrative, she leads the Unified Intelligence Taskforce (UNIT), a military organization dedicated to defend Earth against alien threats, as head of Scientific Research and later as commander-in-chief. She has appeared alongside multiple incarnations of the Doctor, including the War, Tenth, Eleventh, Twelfth, Thirteenth, Fourteenth, and Fifteenth Doctors. The character was received positively for bringing a more sympathetic, science-based approach to UNIT, though critics noted her increasing moral ambiguity in later appearances.