The Doctor Who finale explained - everything you need to know about that ending

Another year and another season of Doctor Who has come to an explosive end. But, as the Fifth Doctor once said, it feels different this time... 

There are a number of reasons for that. Not only are we soon to say goodbye to Peter Capaldi’s 12th Doctor – who started but didn’t finish his regeneration in The Doctor Falls – but also to showrunner Steven Moffat, who departs with his Doctor at Christmas. The episode also provided closure, if not finality, for Bill, Nardole, and the two Masters. 

Then there was the little matter of that ending… As the Doctor fought off regeneration, having decided that he’d rather die than change yet again, someone stepped out of the snowy wastes. “Who is that?” the mysterious figure called out. “I’m the Doctor,” replied our wounded hero. “The Doctor? Oh, I don’t think so. No, dear me, no. You may be A doctor, but I am THE Doctor. The original, you might say!”

That line confirmed something that fans have been speculating for months was true: The First Doctor, originated by William Hartnell in 1963, is back. Now played by David Bradley, of Harry Potter and Game of Thrones fame, he will be joining Capaldi in the Christmas special for a unique twist on the multi-Doctor story. 

That line confirmed something that fans have been speculating for months was true: The First Doctor, originated by William Hartnell in 1963, is back. Now played by David Bradley, of Harry Potter and Game of Thrones fame, he will be joining Capaldi in the Christmas special for a unique twist on the multi-Doctor story. 

Bradley is familiar with both the character and the show. He played the villainous Solomon in 2012’s Dinosaurs on a Spaceship and he starred as William Hartnell in the following year’s biopic, An Adventure in Space and Time, which recreated various scenes from early Who stories. This time, however, he gets to play the real deal, making him the third actor to take on the character (Richard Hurndall took on the role in 1983’s The Five Doctors). 

But why bring this particular Doctor back? What’s the relevance of the setting and why did the Twelfth Doctor choose to hold back his regeneration, anyway? As no solid information has been released about the Christmas special, we can’t say for certain, but I can make a few educated guesses.

Let’s start with the where the TARDIS lands at the end of The Doctor Falls. It’s cold and snowy – rather like Antarctica. That was where the final First Doctor story, 1966’s The Tenth Planet, was set. Not only did that momentous tale introduce the concept of regeneration to an unsuspecting public, it also featured the Cybermen for the first time (and of the Mondasian variant to boot). It’s a safe bet, then, that at least some of the Christmas episode will take place within that story.

“I don’t want to live if I can’t be me anymore,” says Bill, early in the finale, and it’s a sentiment that all the lead characters reflect on at some point in the episode. But while Missy and the Master choose death over change, and Bill and Nardole both accept their new journeys, the Doctor is steadfast. 

He’s old and tired. This incarnation began his life with a major crisis of confidence, then lost Clara, River, and now Bill, before (he thinks) finally being abandoned by Missy. It’s been a rough few years! And so, in the snow, he gives up and accepts death rather than transformation. 

Except, the universe isn’t done with him yet, and so here comes a Doctor to help make him better. The First Doctor is young (despite his looks) and coming to terms with the idea of regeneration, while the Twelfth is a man who has outlived his regeneration cycle and has no end in sight. There’s something rather lovely about the idea of the two of them helping each other accept that change is a natural part of life – especially for a Time Lord.

It was also an episode of endings for the show’s supporting cast. The Master and Missy went out in the most fitting way imaginable – killing each other and laughing about it. No one seriously believes that’s the final end of the character, mind. If one thing’s a given with the Master, it’s that he/she is a survivor. And as we don’t see a regeneration for either here, it would be very easy to bring Gomez and Simm back. 

There’s also some interesting ambiguity over precisely which regeneration Missy is. We’ve all assumed that she follows Simm’s Master, but perhaps she doesn’t. Missy may very well be the last Master, but there’s nothing to say that there aren’t previous (still wicked) regenerations we haven’t met yet.

And what of Bill? Pearl Mackie’s much-loved companion gets an ambiguous but optimistic send-off here. After being converted into a Cyberman in the previous episode, she is saved by the reappearance of Heather, AKA the Puddle Girl from The Pilot. Heather rearranges Bill’s atoms, freeing her from her cyber-body and turning her into a being like herself, but with her human personality intact. The two leave to explore the universe together. 

It’s a sweetly ambiguous moment. Not only does Bill get a happy ending – and the show dodges the horrible dead gay character cliché – but the door is open for her to return. And, unlike Clara (whose transformation into another state of being this recalls), she has the option of becoming mortal again. Heather makes it clear that if she ever wants to be restored, she can be. With that and the character’s popularity in mind it’s surely only a matter of time before we see Bill Potts again – perhaps even as soon as Christmas.

Two Doctors facing the end of their lives, no companions (that we yet know of), and a setting that's almost certainly taken from classic Who... It feels like this will be a fitting and reflective cap to the last seven years of Doctor Who. But a new lead and a new showrunner also make their debut at Christmas, kickstarting the next era. As the First Doctor once said, it's far from being all over...