Spoilers ahead for the latest Doctor Who special, "The Power of the Doctor."

This past weekend Jodie Whittaker's tenure as the Thirteenth Doctor on Doctor Who came to a close at the end of the new "The Power of the Doctor" special. The episode ended with Whittaker's Time Lord regenerating into the next Doctor — who turned out to be David Tennant, exclaiming "What?!" when he realized he was back in the Doctor's body.

Tennant, who played the fan-favorite Tenth Doctor from 2005-2010, wasn't the only one confused. His surprise appearance left delighted fans' heads spinning more than an intergalactic trip on the TARDIS. 

“If you thought the appearance of David Tennant was a shock, we’ve got plenty more surprises on the way!" said Russell T. Davies. The It's a Sin creator was the Doctor Who showrunner during's Tennant's original run, and will return to the helm for next year's 60th-anniversary celebration.

Not only is Tennant's Doctor stepping back inside the TARDIS, but so is his companion Donna Noble, who will once again be played by Catherine Tate. So what does the return of this Doctor Who duo mean for the series?

"Maybe this is a missing story. Or a parallel world. Or a dream, or a trick, or a flashback," Davies teased. "The only thing I can confirm is that it’s going to be spectacular, as two of our greatest stars reunite for the battle of a lifetime."

Tennant and Tate will return in three Doctor Who specials set to air in November 2023 where they will face off against a mysterious new villain played by Neil Patrick Harris.

Sex Education star Ncuti Gatwa, who was previously announced as the next Doctor, is now known officially as the Fifteenth Doctor. Fans got a glimpse of him in a new teaser trailer where we see him shout: "Someone tell me what the hell is going on here!" Our thoughts exactly.

Earlier this year, it was announced that Heartstopper actress Yasmin Finney would also be joining Doctor Who "playing the character of Rose" leaving fans to wonder if this would be the same Rose — played by Billie Piper — who was the Doctor's companion when the sci-fi series was revived in 2005.

"You’ll find out in 2023, but it’s an absolute joy to welcome Yasmin to the Doctor Who set," added Davies. "We all fell in love with her in Heartstopper, one of those shows which changes the world - and now Yasmin can change the Whoniverse!”

At the moment Davies is staying as quiet as a Weeping Angel, but he did offer one final tease for Whovians, saying that "the path to Ncuti’s Fifteenth Doctor is laden with mystery, horror, robots, puppets, danger, and fun!"

Check out the teaser trailer for the 2023 Doctor Who specials below.