| Kate Lethbridge-Stewart | |
|---|---|
| Doctor Who character | |
 Jemma Redgrave as Kate Lethbridge-Stewart | |
| First appearance | Downtime (1995) |
| Last appearance | "Empire of Death" (2024) |
| Created by | Marc Platt |
| Portrayed by |
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| Shared universe appearances |
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| Duration | 1995, 2004, 2012–2015, 2021–2024 |
| In-universe information | |
| Species | Human |
| Affiliation | |
| Children | Gordon Lethbridge-Stewart (son) |
| Relatives |
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| Home | Earth |
| Home era | 21st century |
Kate Lethbridge-Stewart, also known as Kate Stewart, is a fictional character in the British science fiction television series Doctor Who. She was initially created by writer Marc Platt and was played by Beverley Cressman in the independent direct-to-video spin-offs Downtime (1995) and Dæmos Rising (2004). Kate was re-introduced by writer Chris Chibnall in the 2012 episode "The Power of Three" played by Jemma Redgrave, who continued to reprise the role in a recurring capacity through 2024. She will star as a lead character of the upcoming spin-off series The War Between the Land and the Sea, which is set to begin filming in September 2024.
Within the series narrative, Kate Lethbridge-Stewart serves as the head of Scientific Research and later the commander-in-chief of the Unified Intelligence Taskforce (UNIT), an organisation that defends Earth from alien threats. She is a principal ally of the Doctor and the daughter of Brigadier Lethbridge-Stewart, who initially led UNIT during the original run of Doctor Who. Kate is one of the longest-running recurring characters in the show's revived run, appearing alongside the Eleventh, Twelfth, Thirteenth, Fourteenth, and Fifteenth Doctors.