Since the sci-fi series was revived in 2005 by Russell T. Davies, thirteen men have taken on the role of the Doctor, including the late John Hurt, as the War Doctor in the show's 50th anniversary celebration. [...] he did note they're not treating it casually and also spilled a few details on the difficult process he faces as the series prepares for yet another era to begin. "The problem I face -- or anyone in my job faces with a regeneration -- is that we've got to go on an adventure during which [the Doctor is] horrifically injured or something happens to him that causes him to regenerate," says Moffat. "[...] what we're accommodating is a necessary recast," he continues.