7. The Fourth Doctor - Fulton Mackay
Several intriguing and worthy actors were considered to replace Jon Pertwee, amongst them Graham Crowden, Bernard Cribbins and Jim Dale. While each of these men might have had the acting ability, none of them had the strange, alien charisma of Tom Baker. Its hard to imagine any of them escaping from Pertwees shadow in quite the way Tom did and especially hard to imagine it of Fulton Mackay, a TV stalwart and one-time frontrunner for the part. The original concept for the Fourth Doctor was that he would be a much older man, in the vein of William Hartnell. That was, frankly, a terrible idea, because the only way to top Pertwee was to go bolder, madder and stranger. Until the happy accident of Tom Bakers discovery, though, Mackay was what the producers wanted. Though younger than Pertwee, the characters he usually played were either bureaucratic fuddy-duddies or terrifying authority figures. On that basis, its not difficult to see him as Hartnell redux. But while he was a fine actor, he lacked that quality of physicality that all of the Doctors, and certainly Tom Baker, possessed. As it happened, Mackay couldnt commit to Doctor Who anyway, because a pilot he had recently filmed, Porridge, was given a full series. Tom Baker was then cast as the most iconic and long-lasting of the Doctors to date, while Mackay achieved immortality as the ludicrously authoritarian (and self-named) Warden Mackay. Once again, everything worked out for the best.