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Doctor Who ran from 1963 to 1985 when it was canceled. In 1996 they made a TV movie of it. Then, in 2005, Russell T Davies, the famous British drama writer began producing the show again, starting with the Ninth Doctor. He formatted it in such a way that you can watch the new series, starting with Nine, without getting lost in old references. So your best bet is to start with the new Doctor Who series, season one.