Humans can do some regeneration — but most of it happens before we’re born. In humans, an embryo fewer than 8 weeks old can fully regenerate a lost limb — but after 9 weeks, scar tissue appears instead. Researchers are, of course, searching for ways to encourage more regeneration in humans.

You feel the energy racing around your body, both vitalizing and killing you at the same time. A little energy seeps out of your extremities, leaving them feel tingling. Then, in a sudden burst of pain, energy, eurphoria and misery every point in your body feels like it’s exploding.

In some episodes, especially the David Tennant era, he has used the name John Smith. When the Doctor became human to hide from The Family of Blood, he used the name John Smith. No one exactly knows his real name, not even the producers and writers.

Olly Alexander

Ultimately, in “The Time of the Doctor” the Eleventh Doctor reveals that, counting the War Doctor and the Tenth’s aborted regeneration, he is actually in his final incarnation, reaching a point where he is dying of old age after centuries of conflict with the Daleks and others on the planet Trenzalore.

The Twelfth Doctor was electrocuted, blown up and shot by Mondasian Cybermen. Despite that, he willfully stopped his regeneration and decaides not to change, and might’ve stayed that way had he not received a visit from the First Doctor.

This then means that the 13th Doctor is his 12th and final natural regeneration. However, just as they did for The Master, the Time Lords granted The Doctor a fresh set of regenerations (The Time of the Doctor). So as the ’11th’ regenerates, he turns into Peter Capaldi, the first of a new set of 12 regenerations.

When testing Missy’s rehabilitation resulted in Bill becoming a Cyberman, Missy leaving with the Master, and Nardole having to be left behind, the Doctor was mortally wounded in battle against the Cybermen.