5. The Six Doctors
The Five Doctors is a classic Doctor Who episode. It's what a lot of fans hope 'The Day of the Doctor' will live up to, and even Steven Moffat has claimed that it was an episode that he was beside himself with excitement for. But
The Five Doctors was very nearly
"The Six Doctors". Robert Holmes developed the idea for the multi-Doctor story that would focus on all five incarnations of the Doctor being kidnapped by the Master, working for the Cybermen. These Cybermen would be intent on trying to steal the DNA of the Time Lords, and the First Doctor would've been an android, hence the sixth Doctor at the party. In this story, the Second Doctor would've been the one to save the day, which really does beg the question, how bitter would the Third Doctor have been about the resolution?
The plot would later be partially adapted to be used in
The Two Doctors, where Patrick Troughton returned again, alongside Sixth Doctor Colin Baker.