Peter Capaldi

Who's next: End of an era as "Doctor Who" gets a new star

For millions of Britons, a traditional Christmas Day includes turkey, brussels sprouts, Christmas pudding — and a special seasonal episode of "Doctor Who."

The global success of the venerable sci-fi series means that fans around the world will also tune in Monday to watch Peter Capaldi's final adventure as the space-hopping Time Lord known as the Doctor. (Americans can see it on BBC America at 9 p.m. Eastern).

The show has had a dozen Doctors over its 54-year history, and this is one of those bittersweet moments when one lead actor hands over to another. At episode's end, viewers will see Capaldi transform — through a Time Lord process known as regeneration —...

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