Steven Moffat (The Girl Who Loved Doctor Who)

In a parallel universe, Steven worked for Doctor Who, a TV show which chronicled the life of the Doctor. The day before they were to start location filming in 2013, Matt Smith planned to ask Steven to write in a scene like the one he was sharing right then with the Eleventh Doctor, in the episode about the Doctor landing in the "real world".

The Eleventh Doctor asked Matt Smith to suggest the name of Peter Capaldi to Steven, as a potential candidate for the actor to replace himself in the role of the Doctor. (COMIC: The Girl Who Loved Doctor Who)

Behind the scenes
The Doctor is, of course, referring to Steven Moffat, head writer and executive producer of Doctor Who in 2013. A version of Moffat had previously been established to exist within the Doctor's own dimension in the book Decalog 3: Consequences.