John Lucarotti (in-universe)

John Lucarotti was a human in France who, on one occasion, met the First Doctor while dining at a restaurant. The encounter was shocking to him, as while he did know of the Doctor he did not believe that he was real. After the Doctor mentioned St Bartholomew's Day massacre, Lucarotti began to run his eyes, believing that his old age was causing the Doctor to appear. As he did this, the Doctor vanished; seeming to confirm his beliefs. However, when he asked for his check from his waiter, he was informed that the old man he had been talking to had already taken care of his tab. (PROSE: The Meeting)

Behind the scenes
John Lucarotti was a real-world writer who had worked on Doctor Who during the Hartnell era, and who also wrote The Meeting. Although it is not directly explained in the story, the underlining implication is that that character within the story is himself, being visited by a character whom he had once written for.