Doctor Who season 10 just ended with a cliffhanger that none of us saw coming, and if you’re wondering who the mysterious new character is and where they are in the Doctor’s timeline, then check out our explanation!

Obviously, if you haven’t seen the season 10 finale of Doctor Who yet, beware of huge spoilers. If you continue on and you don’t want to be spoiled, then ¯\_(ツ)_/¯.

While we were all staring at the screen waiting for Peter Capaldi’s Doctor to begin his next regeneration, we were caught off guard when that regeneration did not in fact happen.

Instead, somehow, the Doctor was able to halt the regeneration before it really got started and was confronted by a man approaching him through the snowstorm that the Doctor landed in just moments ago.

That man was none other than William Hartnell’s first Doctor. And yes, that was David Bradley reprising the role he played as Hartnell in the BBC TV movie special An Adventure in Time. Except this time instead of playing Hartnell playing the Doctor, it looks like Bradley is actually playing the first Doctor. We know, it’s a lot to take in.

So when in the Doctor’s timeline is this surprising meeting taking place?

A frame from 1966’s The Tenth Planet. These Cybermen exactly match Bill’s appearance in the season 10 finale, and the snowy location appears the same as the final 10 minutes.

Based on the first Doctor’s clothing and the setting of the snowy area, it appears they are in 1986 at the South Pole. This was inspired by William Hartnell’s final episode, The Tenth Planet which premiered in 1966. This episode is also not-so-coincidentally the series’ first look at Cybermen, which brings the whole tale full circle.

Near the end of The Tenth Planet, the Doctor is in a weak state and leaves his current companions, Ben and Polly, for a moment telling them he needs to get to the Tardis immediately.

It’s during this departure that apparently the Doctor runs into his twelfth regeneration, and it looks like the Christmas special will continue the tale of the two Doctors on the brink of regeneration.

This isn’t the first time we’ve been kept waiting to see the regeneration at the end of a Doctor’s life. Most recently Matt Smith’s Eleventh Doctor also waited until the Christmas episode to regenerate into Peter Capaldi’s Twelfth Doctor.

It’s likely that new showrunner Chris Chibnall is going to take the time between now and Christmas to find the next Doctor (and possibly companion?).

If the pattern follows previous announcements, we should get a reveal sometime in the fall or before Christmas announcing who will fill Capaldi’s shoes. They’ll be taking on the role for a whole new Moffat-less era.

But until we find out who that will be, we’ll be here trying to figure out what story Chibnall will be telling us this Christmas that involves the First Doctor and the Twelfth Doctor. Did the the First Doctor go on a secret adventure we never knew about before he met back up with Bill & Polly? We’re about to find out!

What do you think of ‘Doctor Who’s’ season 10 finale?

What are your theories for the Doctor Who Christmas special this year? Are you looking forward to seeing Bradley reprise his role, but as the actual first Doctor?