And here :
The Doctor, like all Time Lords can 'regenerate' into a new body when he dies or is ill and he of course totally rejects the idea of not combating the evil in the universe (having been put on trial twice by his own people for this offence); his biggest enemies are the Daleks (genocidal fascists), Cybermen (Borg get lost) and fellow Time Lord, but opposite , 'the Master' .The Doctor has regenerated many times so far. Herein is the full list -
And the ones only revealed after last year's 50th anniversary special :
I. The eighth doctor regenerates into 'the war Doctor' -
II . The War Doctor regenerates :
here is the latest regeneration after to introduce the New Who, as per the winter special :
'A universe without The Doctor Scarcely bears thinking about'