This long-running British science-fiction program about a time-traveling adventurer known only as “the Doctor” has, over the years, gained an international cult following that spans generations. The original series ran for 26 seasons, going off the air at the end of 1989. A modestly successful Doctor Who TV movie in 1996 was followed in 2005 by the revival of the series. Over the years, 12 different actors have played “the Doctor,” who travels through time and space using what machine? Discuss