There are six occasions where the Doctor has regenerated outside of the TARDIS: one is forced on him by the Time Lords (The War Games); one where another Time Lord aided in the process (Planet of the Spiders); one which resulted in him vacating to the TARDIS's 'Zero Room' to heal, a chamber sealed from all outside ...
It seems that throughout The Doctor's history, he only regenerates in his TARDIS. Heck, even 10 seemed to use his last amount of strength to get in it and fly to space, but then, his regeneration destroyed the TARDIS. 11 destroyed a city with regeneration energy and then had an extremely quick regeneration.
In The Timeless Children, we find out that Tecteun limited the regeneration process to only 12 for each Time Lord; so what's to say that she didn't do the same for the timeless child/doctor because if she can limit the process for everyone then theoretically, she could do the same for the timeless child.
(TV: The Giggle [+]Russell T Davies, Doctor Who 2023 specials (BBC One and Disney+, 2023).) While most regenerations caused Time Lord's to take on an entirely new appearance, it seemed that in very rare circumstances they could regenerate into previous appearances.
The Doctor had given so much to the universe, spent 12 lives fighting for others and wasn't sure he could do it for a whole other set of regenerations. Which is why the Tardis brought him to that moment, to the first Doctor also struggling with the idea of regenerating. To remind 12 and to accept another regeneration.
The Doctor Talks Like His Past Regenerations (With Flashbacks) First, Third, Fourth & Tenth Doctors
What happens to the old doctor when he regenerates?
It is also stated that following the regeneration the Doctor's brain cells would be shaken up and his behaviour would be "erratic" for a time, something that would be evident for most subsequent regenerations.
Why did the tenth doctor take so long to regenerate?
Reasons For The Tenth Doctor's Explosive Regeneration
Peter Capaldi's Doctor delayed his regeneration for a few days as he fought to save the colonists from the Cybermen before apparently dying in the process.
How many times can Doctor Who regenerate? An infinite number of times, apparently – or at least, an indeterminate number. So when the Doctor dies, he or she has the ability to change into a new body as a means of survival, as many times as they need.
Wandering back to his TARDIS through the South Pole in 1986 after leaving his companions behind, the First Doctor refuses to regenerate. He encounters the Twelfth Doctor outside his own TARDIS in a similar state of mind.
Apparently, Time Lords can only regenerate a maximum of twelve times in a single regenerative cycle. After that, they die. However, the Time Lords have been able to give certain members of their society additional regenerative cycles.
PROSE: The Trial of Doctor Who is the only valid story, as this Wiki defines it, that explicitly confirms that "∂³Σx²" is the Doctor's true name. However, this name has not been widely accepted.
Matt Smith, renowned for his role as the Eleventh Doctor, will once again step into the TARDIS, this time as the sixteenth incarnation of the Time Lord, mirroring David Tennant's celebrated Doctor Who return last year.
We may never know for certain, but whatever its genesis, the outcome of this epic conflict was horrifying and only two Time Lords survived - the Doctor and the Master. With the latter's apparent death the Doctor is left to continue his travels with the lonely knowledge that he is the last 'child of Gallifrey'.
He was created as a result of a conscious decision of the Eighth Doctor, played by Paul McGann, to take up arms and become a warrior; in accepting this duty, the War Doctor disowned the title of "Doctor", and after the war's end is viewed with disdain by his subsequent incarnations, who reclaim the title that the ...
Why does the TARDIS always crash after regeneration?
This is because the regeneration energy is so powerful when it hits things it can start fires and when it hits parts of the TARDIS it damages it causing it to crash. We've seen this in the episodes The End Of Time, and The Eleventh Hour when the Doctor regenerates into the Eleventh Doctor.
Doctor Who season 12 revealed the Doctor is not a Time Lord at all; rather, she is the Timeless Child, a billion-year-old being who became the base genetic code for the entire Time Lord race. There's a strange sense where the Timeless Child changes everything and nothing at the same time.
The longest-lasting on-screen incarnation is the Fourth Doctor, played by Tom Baker for seven years. Within the narrative, these changes were explained as regeneration, a biological process which heals a Time Lord when their incarnation is about to die.
This timeline is based upon observations of the Doctor Who universe and the events that occur during each of these stories. The short story Girl Power! suggested that the Master had had a total of eighteen regenerations up to, and including Missy.
Time Lords are extremely long-lived, routinely counting their ages in terms of centuries; the Second Doctor claimed in The War Games that Time Lords could live "practically forever, barring accidents." The series has suggested that Time Lords have a different concept of ageing from humans.
To start with there is a, well, limit. A regenerative 'cycle' consists of twelve regenerations, after which Time Lords are unable to regenerate. This means that the thirteenth incarnation of any Time Lord should be their last. Yet, there's some wriggle room in that, hence the 'should.
The Doctor's original origin story in Doctor Who didn't feature Time Lords at all. Doctor Who season 12 shocked fans by retconning the Doctor's history, revealing she is not a Time Lord at all - but rather is the Timeless Child, a being who may well predate the universe itself.
Why was David Tennants' regeneration so explosive?
The decision to hold onto energy, so he could visit everyone, could have contributed to the explosiveness of his regeneration. When the accumulated and retained energy was finally allowed to erupt, the TARDIS was destroyed, and the Eleventh Doctor was forced to crash-land into Amy Pond's backyard.
However, the Master, unable to accept defeat, fatally wounded the Doctor using the energy beam of a Qurunx, and she regenerated into her next incarnation after amicably parting ways with Yaz. (TV: The Power of the Doctor [+]Chris Chibnall, Doctor Who Centenary Special 2022 (BBC One, 2022).)
In "The Girl Who Died," the Doctor finally remembers that he shares a face with a man he was persuaded to save in Pompeii, despite his initial reluctance to alter the timeline. He surmises that he subconsciously chose this face as a reminder that his job is to save lives.
