Steven Moffat (in-universe)

Steven Moffat was credited with writing down the afterword to a book of fiction about the Doctor, under dictation from a temporally-displaced Professor Candy who had been stranded in 1996 Birmingham by the Doctor. (PROSE: Afterword)

Parallel timelines
In a meta-fiction universe visited by the Eleventh Doctor where his life existed purely as fiction, a certain Steven was the head writer of Doctor Who.