Nine Regenerations... and a Tennanth
As Mark Goodacre observes, the U.K. is in a state of hysteria over the season finale of Doctor Who, in particular the question of how David Tennant's regeneration will resolve itself. Anyone who's been following the media knows that Tennant will still be our Time Lord hero next year, but it will be fun to see how that works out this afternoon. Will it be a non-regeneration? Will he regenerate into himself (with the help of his twice-regenerated hand from two seasons ago)? Or will he regenerate into someone else, be killed, and then supplanted by a Tennant from an alternate universe?
In the meantime, check out the following youtube clips of Doctor Who's previous regenerations. I like how each incarnation reacts and recovers differently to the process: Pertwee slumbered in a near coma for two whole episodes, Tom Baker was hyper-manic, Davison suffered a multiple personality crisis (imitating each of his four previous selves in turn), and Colin Baker -- my favorite, though quite controversial -- became homicidal and tried to strangle his own companion (Peri). (Tennant was a cross between Pertwee and T. Baker: manic with Rose in the TARDIS, then comatose through two-thirds of The Christmas Invasion).
William Hartnell to Patrick Troughton, Patrick Troughton to Jon Pertwee, and Jon Pertwee to Tom Baker
Tom Baker to Peter Davison, and Peter Davison to Colin Baker
Colin Baker to Sylvester McCoy, Sylvester McCoy to Paul McGann, and Christopher Eccleston to David Tennant.