Doctor Who: How many more times can the Doctor regenerate?

David Tennant; Matt Smith; Peter Capaldi

Peter Capaldi has been announced as the latest star of Doctor Who. But how many more times can the Doctor regenerate, asks Ben Milne.

Among Doctor Who's hardcore fans, it's an accepted part of Whovian mythology that Earth's favourite Gallifreyan can only have 12 regenerations. Capaldi is the 12th Doctor, so does this mean he's the penultimate?

The idea that the Doctor has 12 regenerations is first mentioned in The Deadly Assassin, a 1976 episode from the Tom Baker era. The Master - an evil Time Lord close to his final regeneration - is said to have been offered a new cycle of lives in exchange for helping to rig the election of a new Time Lord leader.

He fails, but in a later series we see him get around the regeneration problem by stealing the body of a dupe called Tremas (an anagram of… well, you get the point). The idea is mentioned again in the show's 20th anniversary special, The Five Doctors.

There are said to be some fans so hardcore that they say they will not watch the show if the Doctor survives beyond his 12th regeneration. However, this is the sort of thing which hardcore fans tend to say.

The fact is that Doctor Who's producers have often played fast and loose with "the laws of time and space" - for instance, the Doctor's only ever time lord (or lady) companion, Romana, apparently possessed the ability to regenerate several times before breakfast, trying on several different appearances before transforming from Mary Tamm to Lalla Ward.

It might be that if the programme retains its popularity, the producers will find a way to get round this dilemma. It remains to be seen whether it's as drastic a solution as the recent Star Trek film which used time travel (the plot device which keeps on giving) to effectively wipe out the entire "history" of the Star Trek universe.

Image caption The Master (left) with Tom Baker as the Doctor

But ultimately, one doesn't need a sonic screwdriver to realise the Doctor's continuing existence will owe less to the laws of the space-time vortex than the health of the TV ratings.

Here is a selection of your comments from Twitter and Facebook

The regenerations in the new series are different from the original series. The Master even managed to regenerate. So a different type of regeneration may be in use allowing many more regenerations.

Andrew Swallow

I hope that Moffat & co. will find a way to break the rule of 12 regenerations. I mean, from that point of view, that rule has already been broken by adding John Hurt as the forgotten regeneration between McGann and Eccleston, which makes Capaldi already the 13th Doctor.

Jovana Filipovic

There can be one more. Though I know two ways the whole 13 Doctors thing can be broken. Both are possible. One is River's regenerations, the other is that the rule is a law that was passed in Gallifrey, not a biological thing.

Isabelle Frater

The regeneration limit was a rule enforced by the high counsel, not a biological limit.

Stacee Knouse

The master exceeded his 12 so the doctor can too.

Sandi Dubrow Eltawar

River gave him all but three of her regenerations. He has a few more to go.

Kaylee Nichole Lopez

But John Hurt's actions were not done "in the name of the doctor".... So, I a sense, Capaldi still is the 12th Doctor... Right? *its too early in the morning for my brain to think this hard*

Jaime Carter Green

Then if you watch the Sarah Jane Adventure - the Death of the Doctor - he is asked how many times - he replies 507.

Kimberlee Haver Finne

But he also used one in the stole earth episodes but didn't actually change. That'll count towards the total, no?

Daryl McLean

The 12 regenerations limit removed. Can't remember which, but RTD changed to unlimited in a 10th Doc episode

Jamie Rose, @MrJ_Ro

It was an episode of the Sarah Jane Adventures with Matt Smith in it. *showing my geek credentials*

Rob McConnell, @RobMcConnell