Companion Millie Gibson to Depart 'Doctor Who' After a Single Season

The one constant in the world of Doctor Who is change. It's been embedded in the very fabric of the show's DNA since the very beginning. People usually cite the process of regeneration to prove this point, the means by which the various actors who have played the Doctor have swapped in and out of the role since Patrick Troughton first replaced William Hartnell in 1966. But the same has also always been true of the Doctor's companions, who've been popping in and out of the TARDIS virtually since the series started. Some of the Doctor's friends have stayed for multiple seasons, and some just a handful of episodes, but each has been irrevocably changed in some way by their adventures with the infamous Time Lord. But that doesn't make the process of saying goodbye any easier, particularly when it's someone we feel like we've only barely gotten the chance to know.

Such will apparently be the case for Millie Gibson, who is leaving the show after a single season. Gibson's Ruby Sunday, the first companion of Ncuti Gatwa's Fifteenth Doctor, was introduced in the 2023 Christmas special, "The Church on Ruby Road," and will star in the series' upcoming fourteenth season, which is set to premiere in May. But Variety has confirmed that she won't be part of the show's currently filming Season 15, and has been replaced by Andor actress Varada Sethu.

No other details about Sethu's role have been revealed and neither the BBC, Bad Wolf, or showrunner Russell T. Davies have commented on the casting reports as yet. (But the report has not been denied and Gatwa himself posted an Instagram story that felt like a comment on the larger casting discourse.)