Doctor Who fans have been thrown for a loop, with David Tennant returning to the show on Sunday, October 23, reprising his role as the Time Lord as Jodie Whittaker's 13th Doctor regenerated.
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The big reveal happened at the end of the 90-minute special The Power of the Doctor, which saw Jodie, 40, take on familiar foes the Daleks, the Cybermen, and the Master.
SNEAK PEEK: David Tennant returns to Doctor Who
There were a host of familiar faces featured in the episode including former Time Lords Peter Davison, Colin Baker, Sylvester McCoy and Paul McGann. One of the Doctor's first companions William Russell, 97, also made an appearance, as did Sophie Aldred, Janet Fielding and Katy Manning.
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As Jodie's character regenerated, fans expected her to morph into her previously announced successor—Sex Education's Ncuti Gatwa. Instead, the Doctor returned as David, 51, who played the Time Lord from 2005 to 2010. As he was revealed, he whispered, "I know these teeth," before exclaiming, "What?!"
"It was a total joy from start to finish," David Tennant said of returning to the role
The Good Omens actor is reprising his role across three special episodes for the show's 60th anniversary, which are set to air in November 2023. Catherine Tate is also returning to her role as the Doctor's companion, Donna Noble, and Neil Patrick Harris is joining the cast.
Catherine Tate left Doctor Who in 2010
It was announced earlier this year that David and Catherine, 54, were filming scenes for the show's 60th anniversary, but fans were expecting his reappearance to only be a cameo.
"What a lovely, lovely thing to get to revisit something that was such a wonderful, happy, significant time in my life," he told BBC News.
"I thought it was something that I would certainly never be as involved in again," he added. "It's like being given the loveliest present. And I'm very, very excited. I'm thrilled and I hope people will enjoy the stories we've got to tell."
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We'll have to wait to see what awaits the Doctor's companion, Donna, which David confirmed was "a big mystery."
"As eagle-eyed viewers will know, when we last left Donna Noble, she could not remember the Doctor's existence, or her brain would melt. So there's a bit of an issue there," the Broadchurch alum told the BBC.
Talking about what happens next, Russell T. Davies, the series' showrunner said, "If you thought the appearance of David Tennant was a shock, we’ve got plenty more surprises on the way! The path to Ncuti’s 15th Doctor is laden with mystery, horror, robots, puppets, danger and fun! And how is it connected to the return of the wonderful Donna Noble? How, what, why? We’re giving you a year to speculate, and then all hell lets loose!"
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