To celebrate the 50th anniversary of the world's longest-running S.F. series, BBC America is going back in time to pay tribute to every incarnation of Doctor Who, from William Hartnell, the original time-traveller, to Matt Smith, the current occupant of the TARDIS. Every month throughout 2013, The Doctors Revisited will look back at the adventures in time and space of one of the eleven Doctors, featuring discussions with contributors to the show, past and present.