TV Ncuti Gatwa makes game-changing debut on Doctor Who The show's final 60th-anniversary special episode had a big surprise for fans. By Clark Collis Clark Collis Senior Writer EW's editorial guidelines Published on December 9, 2023 03:45PM EST Warning: This article contains spoilers for the Doctor Who 60th-anniversary special episode "The Giggle." "Now someone tell me what the hell is going on here!" That was the demand of Ncuti Gatwa's Fifteenth Doctor shortly after the character made his much-anticipated debut on Saturday's final 60th-anniversary episode of Doctor Who. And he doubtless echoed the thoughts of many Whovians. While fans of the show had long assumed that Gatwa would take over the role of the Time Lord from David Tennant in the course of the episode, titled "The Giggle," the manner in which that occurred was most definitely a surprise. After Neil Patrick Harris' villainous Toymaker shot Tennant's character through the chest with a laser, it looked as if the actor's version of the two-hearted alien would vanish before our eyes. Traditionally, in such circumstances, the Doctor's body "regenerates" completely into its next iteration, leaving no physical trace of the previous one. On this occasion, however, Gatwa's time traveler emerged from Tennant's Time Lord, meaning viewers were treated to two Doctors tackling the Toymaker. "I have bi-generated," Gatwa's Doctor explained to his friends, including Catherine Tate's Donna Noble and Bonnie Langford's Mel Bush. "There's no such thing. Bi-generation is supposed to be a myth, but look at me!" Ncuti Gatwa on 'Doctor Who'. BBC After the Doctors defeated the Toymaker, Gatwa's character created a twin TARDIS for Tennant and then headed off for new adventures, leaving his previous version to live something close to a normal life on Earth. Does this surprise plot development mean we will be seeing more of Tennant on the show? Most likely. Certainly the actor enjoys playing the Time Lord. His initial five-year run on Doctor Who concluded at the start of 2010, but he returned for 2013's 50th-anniversary special and then came back again for this year's trio of 60th-anniversary episodes. When EW asked him if he would reprise the role for the show's 70th anniversary, Tennant replied, "Who knows if I will still be able to run up and down corridors. I was pleasantly surprised that I didn’t damage my knees this time out, so I wouldn’t want to tempt fate. But should my joints still be in working order, I will certainly consider any offers if they come through in 10 years' time." Meanwhile, Gatwa will definitely return as his new version of the Time Lord on this year's Doctor Who special Christmas episode, which premieres Dec. 25 on Disney+ . Watch the trailer for it below. Sign up for Entertainment Weekly's free daily newsletter to get breaking TV news, exclusive first looks, recaps, reviews, interviews with your favorite stars, and more. Related content: Doctor Who star David Tennant says returning for 60th anniversary shows was 'an unexpected treat' Millie Gibson cast as new Doctor Who companion