Spoilers for Doctor Who follow.
Doctor Who aired its long-awaited regeneration episode tonight with Jodie Whittaker taking her last bow as the 13th incarnation of the Time Lord.
In 'The Power of the Doctor', the Doctor battled the Master (Sacha Dhawan) and his legion of Cybermen and Daleks as the Master schemed to force the Doctor to regenerate into him. It worked for a short while, but with the help of Yaz (Mandip Gill) and Vinder (Jacob Anderson), the Doctor managed to thwart the Master's plan.
However, just when the Doctor thought she'd won, the Master managed to mortally injure the Doctor. Soon after, the Doctor’s right hand begun to ominously glow — signalling an upcoming regeneration. The Doctor and Yaz used their last minutes to watch Earth from space and enjoy some ice cream, sharing a touching moment together.
Related: Doctor Who's Jodie Whittaker reveals surprise about her last day on set
"A wise person once said to me, 'Goodbyes only hurt because what came before was so special' – and it's been so special," the Doctor said to Yaz. "You and Graham and Ryan and Dan. Nobody else got to be us. Nobody else got to live our days. Nobody. And my hearts are so full of love of all of you.
"I have loved being with you Yaz. And I have loved being me. I think I need to do this next bit alone."
The Doctor then entered the Tardis alone while Graham led a reunion full of the Doctor’s previous companions, where they agreed to meet up regularly and exchange stories about their various adventures with their various Doctors.
Meanwhile, in the Tardis, the Doctor asked the Tardis to "look after the next one" before taking in one last sunrise. "Oh, the Blossomiest Blossom. It’s the only sad thing. I want to know what happens next. Right then, Doctor-whoever I’m about to be, tag. You’re it," she said.
Related: Doctor Who’s Jodie Whittaker teases “stripped-back” regeneration scene
The regeneration then took full effect and David Tennant’s 10th incarnation of the Doctor emerged.
"I know these teeth," he said, before checking out his (not so) new body. "What? What? What?" The episode then ended, setting up a lot of questions for the upcoming special episodes.
Some fans had expected the Doctor to regenerate into Ncuti Gatwa, who has been confirmed as the new Doctor, but that is a mystery that will have to wait for next year. For now, fans are overwhelmed to see Tennant back as the Doctor.
Related: Doctor Who's Russell T Davies discusses Ncuti Gatwa's 'thunderbolt audition'
One fan wrote: "9 year old me who sobbed for a week once David Tennant regenerated is throwing a fucking party right now." While another wrote: "Omg, David Tennant back as the doctor, best regeneration ever."
In particular, fans have been hit with a wave of nostalgia after Tennant's return, with one fan writing: "Seeing David Tennant back on screen as the doctor has slightly healed my inner child."
Doctor Who airs on BBC One in the UK. In the US, the show airs on BBC America, with series 1-12 available on HBO Max. Classic Doctor Who streams exclusively on BritBox in the UK.