Watch Doctor Who's New Star Jodie Whittaker Debut In Christmas Special Regeneration

Say goodbye to the Doctor and hello to the Doctor. Doctor Who star Peter Capaldi made his official departure from the long-running BBC series at the conclusion of the 2017 Christmas special, capping his three seasons as the titular Time Lord.

With his regeneration imminent, Capaldi's Doctor didn't look back on his adventures through space and time, but instead gave advice to his next incarnation. "Never be cruel, never be cowardly," he says. "And never, ever eat pears!" He also proclaims that hate is always foolish and love is always kind, which is ironic given how crabby and angry Capaldi's version of the Doctor was early in his tenure on the show.

"Always try to be nice and never fail to be kind," he says. "And you mustn't tell anyone your name. No one would understand it anyway. Except children. Children can hear it sometimes, if their hearts are in the right place, and the stars are too. Children can hear your name."

Then, with his old body giving way to regeneration, he offers his final words. "Laugh hard, run fast, be kind," Capaldi says, words that apply to both the character and the actor stepping into the role. "Doctor, I let you go."

From there, the golden energy shoots out of his hands and head, making way for Jodie Whittaker--the show's first female lead ever--to make her first appearance on the TARDIS and her first words as the Doctor. "Oh, brilliant," she with a smile says after seeing her reflection. Then, with the push of a button, the TARDIS is thrown into chaos as it malfunctions. The Doctor is flung out the door and into the emptiness of space as a fire explodes inside that trademark phone booth, causing it to disappear to somewhere else in space and time.

"To be continued," the screen then reads. That uncertainty of the future of the Doctor and the TARDIS will remain with Doctor Who fans until the next season of the series debuts. A premiere date has yet to be announced for the new episodes, which see Broadchurch creator Chris Chibnall taking over as showrunner.

You can see the full video of the regeneration above. Below, you'll find a behind-the-scenes look at the filming of Capaldi's final scene, with commentary from now-former showrunner Steven Moffat and director Rachel Talalay.