10 Insane Doctor Who Plot Twists That Nearly Happened

William Hartnell helmed the ship for almost three years before his health issues caught up with him. It was decided that the Doctor should have the ability to cheat death by changing his face and body, thus giving birth to one of TV's greatest ever plot devices.

Hartnell said goodbye in the serial The Tenth Planet, essentially dying of old age. The actor's exit was almost different though - very different indeed.

Producer John Wiles - who didn't necessarily have the best working relationship with Hartnell - tried to write him off during the serial The Celestial Toymaker.

His plan was to have the titular villain turn the Doctor invisible, and, when this was reversed, the Doctor would reappear with a different face. Surprise! This would lead to speculation among his companions as to whether he was the Doctor, or just another of the Toymaker's tricks.

In the end, this proto version of regeneration was nixed, Hartnell's contract was extended, and it was actually Wiles that changed face, with somebody else taking his place as producer. Ironic.