Doctor Who had a fresh way of ensuring survival: having the lead character, The Doctor, with the ability to regenerate, experiencing a complete physical change, this could allow a different actor to continue where the former actor leaves off. A certain flexibility also existed, where the actor could add his own interpretations of the Doctor's nuances and foibles, script rigidity notwithstanding. Since 1963, eight actors have played the role of the Doctor, until its end in 1996, with the shortest tenure being held by Paul McGann, who was cast only for the TV Movie in 1996. Some of the players have received much praise, such as Tom Baker, the infamous "Fourth Doctor" whose tenure was the longest, eight years. Others have endured criticism, such as Peter Davison (The Fifth Doctor) and Colin Baker (The Sixth Doctor).
Lay the blame wherever you like for why the show had weaknesses; over the course of 26 contiguous years, every aspect of the making of the show would be bound to be at fault at one time or another. Of particular note would probably be the production values, as the BBC had only decided to shell out the big bucks for epic production technology in the past ten to fifteen years, so the early years of Doctor Who, especially in the early 1980s, looked cheesy. Still, the show has amassed millions of fans worldwide and fandom did not waiver during those dark years following the show's end. Doctor Who lives!