Ncuti Gatwa is leaving Doctor Who, with the character regenerating as Billie Piper during the finale of the science-fiction series.

The Doctor Who show runner, Russell T Davies, said: “What a Doctor! Thank you, Ncuti! As his final words say, this has been an absolute joy, and the team in Cardiff and everyone who has worked on this show for the past few years are so lucky to have been part of Ncuti’s great adventure as he shoots off to stratospheric new heights.”

In a statement released by the BBC, Gatwa said: “You know when you get cast, at some point you are going to have to hand back that sonic screwdriver and it is all going to come to an end, but nothing quite prepares you for it.

“This journey has been one that I will never forget, and a role that will be part of me forever.”

Piper, 42, starred as the companion to the ninth Doctor in 2005, playing Rose Tyler alongside Christopher Eccleston’s Time Lord.

She said of her shock return: “It’s no secret how much I love this show, and I have always said I would love to return to the Whoniverse as I have some of my best memories there, so to be given the opportunity to step back on that Tardis one more time was just something I couldn’t refuse, but who, how, why and when, you’ll just have to wait and see.”

The finale also saw Whittaker, the 13th Doctor, make a guest appearance as Gatwa’s Doctor appeared to be travelling through alternate universes.

The final episode of this year’s series, The Reality War, was simultaneously broadcast on BBC One and shown in cinemas around the UK, as well as receiving a streaming release on iPlayer and Disney+ internationally. The BBC had not allowed previews for reviewers in an attempt to preserve secrecy around the ending.

Gatwa was the 15th main lead of the show, which originally ran from 1963 to 1989, and was then revived by Davies in 2005, with Eccleston in the role. Since then David Tennant, Matt Smith, Peter Capaldi and Whittaker have been the Doctor, with Jo Martin and John Hurt also guest starring as mysterious versions from the Doctor’s past. Piper, Catherine Tate, Karen Gillan, Jenna Coleman, Bernard Cribbins and Bradley Walsh have been among the Doctor’s companions during the modern era.

David Tennant as the Doctor and Catherine Tate as Donna Noble in 2008. The pair returned to the show for a series of 60th-anniversary specials in 2023. Photograph: Everett Collection Inc/Alamy

In September 2021 the BBC announced that Davies, the Queer as Folk and It’s a Sin creator, would return as show runner for a second time. Since 2023 the show has been co-produced by Bad Wolf and BBC Studios, and has been distributed internationally by Disney+, in a deal which dramatically enhanced the budget for a series that during the 1970s had a reputation for wobbly sets, primitive VFX and monsters made with bubble wrap.

The current era of the show has endured historically low ratings for the series, with the most-watched episode this year – The Interstellar Song Contest, which aired just before the Eurovision song contest it was modelled on – being watched by 3.75 million people in the UK during its first seven days on iPlayer.

The casting of the first woman to play the role, and the first Black actors to pilot the Tardis, have dragged the show into online culture wars about diversity, which the cast and crew have pushed back on.

Varada Sethu, who plays the Doctor’s companion Belinda and who also recently appeared in the Disney+ Star Wars series Andor, said of people calling it “Doctor Woke” that “Woke just means inclusive, progressive and that you care about people. And, as far as I know, the core of Doctor Who is kindness, love and doing the right thing.”

A Doctor Who spin-off series, called The War Between the Land and the Sea, starring Russell Tovey, Gugu Mbatha-Raw and Jemma Redgrave, is expected to air later in 2025.