Mr Tickle
From Tardis Wiki, the free Doctor Who reference
Mr Tickle was a fictional character with his own series of books.
Bernice Summerfield made a mental note to herself once: "Dear diary, I’m not writing this down – if I could I’d be Mr Tickle – so I’m going to have to memorize this, or paint it on the walls." (PROSE: Falls the Shadow)
The Tenth Doctor asked Rose Tyler if she wanted to meet Mr Tickle, but then decided that he might be annoying since he lived in a universe of nominative determinism. (AUDIO: Infamy of the Zaross)