Doctor Who was a character created by Martin Bannister in an alternate universe for a failed television pilot in the 1960s.
When Bannister was in a nursing home, he began to confuse fantasy and reality. He started to believe he was the Doctor Who character he had created decades previously. In the fantasy, he travelled in his TARDIS with Susan (based on his second wife Amy), Ian (based on his son Philip) and Barbara (based on his nurse at the home). Bannister eventually succumbed completely to the fantasy. (AUDIO: Deadline)