What is Regeneration?

“Time Lords have this little trick. It’s sort of a way of cheating death. Except…it means I’m gonna change.”  

The Doctor seemingly never dies! They’re thousands of years old yet they can still look young (some incarnations more then others), and they do it all with this one weird trick… Regeneration!  

The Doctor has had many lives, each with their own unique face. But what is regeneration? Why can the Doctor do it? And how many times?   Here’s everything you need to know about the Doctor’s most important and unique ability…  

How does the Doctor survive?  

Whereas humans are not designed to withstand the harsh conditions of space-time travel, such as free-falling through space, exposure to lethal levels of radiation, or even absorbing the energy from the Time Vortex, Time Lords are a little more hardy. Regeneration is a power that grants a Time Lord another chance at life when their body is too old or damaged to continue. Every cell in their body goes through a process of death and rebirth, essentially transforming them into a brand-new person!  

It’s not just their face that changes. Their personality, their likes and dislikes, even their  gender could all wind up completely different! However, they retain the memories of their previous lives. No matter how different they may look and act, a Time Lord will always be the same person where it counts the most, in their hearts (Time Lords have two!).

Who can regenerate?

Regeneration is an ability primarily associated with Time Lords – high-born Gallifreyans who studied at a place called the Academy. Prior to them, there was no other species known to regenerate in the way that Time Lords do, at least in our universe. 
 

However, there have been others known to possess the ability. As a child of the TARDIS, River Song was exposed to the Time Vortex in the same way as the Time Lords – as children, they looked into the Time Vortex through something called the Untempered Schism, giving them the ability to regenerate. Davros, the architect of the Daleks – the Doctor's most notorious foes – once attempted to steal the Doctor's regeneration energy to create a race of Daleks that could regenerate. Additionally, the Master – a malevolent Time Lord and another of the Doctor's nemeses – successfully converted the Cybermen into CyberMasters. These CyberMasters, created from deceased Time Lords, inherited the ability to regenerate. 
 

The Time Lords did not originally possess the ability to regenerate – They stole it from the Timeless Child, a being of unknown origin who was transported to our universe through a wormhole.

Does regeneration equal immortality?

In short, no. If a Time Lord is killed mid-regeneration, the process will end and they will die. The Master once managed to prevent his own regeneration and allowed himself to die in order to spite the Doctor – although he did so with a plan of his eventual resurrection!

Regeneration is made possible by the aptly named regeneration energy. However, this energy is a finite resource within a single Time Lord, enabling them to regenerate a maximum of 12 times with 13 bodies. A Time Lord’s thirteenth ‘death’, then, is permanent.

Regeneration energy has healing properties, and in very rare cases, it has been used outside of regeneration itself to breathe life back into other people or objects, such as when the Doctor sacrificed 10 years’ worth of his life to repair the TARDIS.

At the height of their power, high-ranking Time Lords had the ability to revive those they deemed worthy. Though rare, both the Master and Time Lord President Rassilon are examples of Time Lords who have been resurrected from the dead. The Time Lords can also grant new regeneration cycles if they wish, giving the lucky recipient a whole new lease of life. For instance, when the Doctor faced certain death on Trenzalore, the Time Lords bestowed such a gift on him, meaning it’s currently unknown how many times they are able to regenerate!

What happens after regeneration?

Understandably, those who have recently regenerated do often wind up a bit frazzled, being a brand new person. The Twelfth Doctor became a bit tetchy and forgot the name of his companion. The Tenth Doctor needed a massive kip before he could fully be himself again, and the Eighth Doctor forgot who he was entirely. It's understandable that when everything you thought you were dies and you become completely new, you need a little bit of time to compose yourself. Companion Amy Pond can certainly attest to the post-regeneration oddities, experiencing the Eleventh Doctor’s at three different points in her life, including his… unique… food cravings.

Although it may seem like the process is over in a flash, a Time Lord’s body continues rearranging itself for hours after the regeneration. The Tenth Doctor was even able to regrow his hand after it was cut off by an alien Sycorax Leader on Christmas Day, thanks to the residual cellular energy from the regeneration.

Once the process itself is over, the Time Lord then faces the unique challenge of getting accustomed to their new body. The Thirteenth Doctor said it was like being a stranger to herself. “There’s echoes of who I was, and a sort of call towards who I am.” Luckily, the Doctor always has their friends to help them rediscover who they are!

How many times has the Doctor regenerated?

Although David Tennant plays the Fourteenth Doctor, this incarnation is technically the sixteenth, meaning, since the First Doctor, there have been fifteen regenerations. But why do two regenerations seem to be unaccounted for? Well, the Tenth Doctor (also played by David Tennant) was shot by a Dalek, and he was able to divert the regeneration energy into his severed hand (the one that was cut off previously on Christmas Day!) to prevent himself from changing. However, this did use up one of his regenerations, meaning that the Tenth Doctor is actually the tenth and the eleventh!

…Or he would be if it weren't for another secret Doctor who existed between the Eighth and Ninth. The War Doctor (played by John Hurt) got his name from fighting in the Time War. This incarnation did things that his future selves would look back on with shame, so much so that they denied the existence of this Doctor…until they crossed paths with him again, although that’s another story.

And remember the Timeless Child mentioned earlier? That mysterious adolescent was in fact the Doctor, from long before they chose their name. It’s possible that the Doctor had an indefinite number of lives before the one that we would consider the First, one of them being Jo Martin’s Fugitive Doctor.

Where do the faces come from?

One of the enduring mysteries for Doctor Who fans concerning the Time Lords is the origin of their bodies. How does the Tenth Doctor immediately have perfectly coiffed hair? Where did the Third Doctor’s tattoo come from? Why did the Second and Fourteenth Doctors come with clothes? It’s as if those bodies were pre-existing somewhere…

Indeed, some Doctors have shared their faces with others in the Whoniverse. The Sixth Doctor bore a striking resemblance to fellow Time Lord, Maxil, while the Twelfth Doctor was the spitting image of Lobus Caecilius, a man from Pompeii whose life he saved. “Who frowned me this face?” he asked himself upon seeing his lined visage for the first time. It wasn’t until much later that he realised that he was conveying a message to himself. He chose that face as a constant reminder of his identity and purpose – he’s the Doctor and he saves people!

For reasons currently unknown, the Fourteenth Doctor looks exactly like the Tenth. It’s not the first time we’ve seen a Doctor return to a previous face. If the Curator (seen in The Day of the Doctor) is indeed a future Doctor, it's possible that one day they might choose to revisit the appearance of their fourth incarnation.

However, the return of the face of the Tenth Doctor to the Fourteenth does not appear to be one that the Doctor was anticipating. “I don’t know who I am anymore.” he laments in the trailer for the Sixtieth Anniversary Specials. Perhaps he might soon find out…

Who came up with Regeneration and why?

From the show's perspective, the concept of regeneration is fundamental, enabling Doctor Who to endure and evolve indefinitely. It’s a programme that has always embraced change, most notably in its interchangeable lead role – and all the while the character of the Doctor remains consistent.

When William Hartnell’s tenure as the First Doctor came to its end, producer Innes Lloyd and script editor Gerry Davis came up with the concept of ‘renewal’. Given that the Doctor was an alien, such a transformation would not be out of the ordinary. The Second Doctor described this process as “part of the TARDIS”, essential for his survival. The transition to the Third Doctor, however, was framed differently – as a punishment by the Time Lords, later known as forced regeneration. The term regeneration itself wasn’t used until the 1974 episode Planet of the Spiders. And looking at everything that’s followed, that term seems to have stuck!

Why not catch up on all the Doctor’s previous regenerations with this handy compilation?