Doctor Who's Kate Stewart Spin-Off - What We Know So Far

While most television series struggle with their ratings and lose viewers when the actor playing the main character changes, "Doctor Who" has made it one of the key features of the show. When the original Doctor William Hartnell began having health problems three years after the show began, "Doctor Who" had become a phenomenon. Instead of canceling the show, the writers devised the ingenious idea of having the doctor "regenerate" when he's on the verge of death, allowing another actor to take his place. The move worked brilliantly and allowed the show to continue each time the lead actor left the show.

Along with the success of "Doctor Who" came popularity for the characters, such as Sarah Jane Smith (Elizabeth Sladen), the companion of the third (Jon Pertwee) and fourth (Tom Baker) Doctors. After reappearing 20 years later in the "Doctor Who" revival and with the tenth Doctor (David Tennant), the spin-off "The Sarah Jane Adventures" was created in 2005, and in 2006, thanks to the popularity of Jack Harkness (John Barrowman), the series "Torchwood" was also created. While we haven't had any more spin-offs since both those series ended in 2011, returning showrunner Russell T. Davies envisions "Doctor Who" expanding its universe like "Star Trek," and finally released some details about the upcoming spin-off featuring Kate Stewart, played by Jemma Redgrave. Here's what we know so far.

In December 2022, at the "Wales Comic Con: Telford Takeover," many fans were asking Jemma Redgrave whether there would be an expanded story about Kate Stewart and UNIT (Unified Intelligence Taskforce). Each time, she suggested to fans that they write to Russell T. Davies and convince him that she deserved a spin-off. "I've worked with some extraordinary people, and some amazing Doctors, and I haven't yet been able to work with the classic Doctors," she told the audience. "But I'm hoping, maybe if there's ever a spin-off — which you're going to write to Russell T. Davies about — that it might happen." Three months later, we're now getting details that Redgrave's spin-off dream is coming true.

The spin-off will focus on Kate Stewart and her running of UNIT to defend Earth from threats from aliens and other planets. Kate's father, Alistair Gordon Lethbridge-Stewart (Nicholas Courtney), founded UNIT after meeting the second Doctor (Patrick Troughton). When the 11th Doctor (Matt Smith) first meets Kate, he mentions her father affectionately and comments on her following in his footsteps.

By the incarnation of the thirteenth Doctor (Jodie Whittaker), she tells MI6's C (Stephen Fry) that UNIT is gone. Fortunately, by Season 13, we see Kate again, determined to keep UNIT alive, and by Episode 9 ("The Power of the Doctor"), they have a new building and are increasing their intelligence units, ready to help the Doctor battle the latest threats, which should continue with the spin-off.

So far, Jemma Redgrave is the only actor confirmed for the spin-off, returning to play Kate Stewart, the role she made popular in 2012. Redgrave is part of the famous Redgrave acting family that includes her grandfather, Michael Redgrave, father, Corin Redgrave, aunts Vanessa and Lynn Redgrave, and cousins Joely Richardson and Natasha Richardson. She's had an extensive acting career that's included the theater, starring in Anton Chekhov's "The Three Sisters" with her aunts Vanessa and Lynn in 1990, as well as Joe Penhall's "Mood Music" with Ben Chaplin as recent as 2018.

In television, Redgrave starred in "Bramwell" for four seasons as the opinionated but empathetic Dr. Eleanor Bramwell, in which she reprised her role for "Bramwell V" in 2000. In 2004, she played MI6 Agent Emily Tuthill in "The Grid," as well as Eve Granger in "Cold Blood," and Dr. Zoe Evans in "Frankie." Most recently, she starred as Bernie Wolfe in four seasons of "Holby City." She left the series during Season 20 but returned for Season 23 (via IMDb).

Redgrave is listed in the credits for the upcoming Season 14, Episode 1 with the future Doctor played by Ncuti Gatwa, and is also expected to appear in the 2023 "Doctor Who" Christmas special.