506. Regeneration

Sameth on Jan. 9, 2013

Well, The Doctor has an ally (who later joined a government agency called “Torchwood”) named Captain Jack Harkness who can also regenerate without changing his appearance. His regeneration is probably a touch under Wolverine's. I'm not sure.
And the whole reason The Doctor got it, of course, was so they could switch actors without having to get someone who looked the same as the previous actor.