The next Doctor Who is going to be......

[pocaracas]

In the long running British science fiction television series Doctor Who, regeneration is a biological ability exhibited by the Time Lords, a race of fictional humanoids originating on the planet Gallifrey[note 1]. This process allows a Time Lord who is old, wounded or otherwise dying to undergo a transformation into a new physical form and a somewhat different personality.

This is not entirely correct.  A better phrasing might be  '...regeneration is a plot device used to save the cash-cow 'Doctor Who' when William Hartnell's health began to decline in the mid 1960s.'

Boru

Both are correct...
One applies to the fictional universe, the other applies to our real universe.