Peter Capaldi (in-universe)
From Tardis Wiki, the free Doctor Who reference
In a parallel universe that the Eleventh Doctor once was stranded in, he discovered a television series about his life. After meeting Matt Smith, the Doctor recommended to him that Peter Capaldi should be the next actor to portray the Doctor.
The Doctor also mentioned that he had once saved Peter Capaldi in his universe from a Mandrel. (COMIC: The Girl Who Loved Doctor Who)
Behind the scenes
The real Peter Capaldi later played the Twelfth Doctor, taking over from Matt Smith's Eleventh Doctor.
It is not actually clear within COMIC: The Girl Who Loved Doctor Who if Peter Capaldi actually exists within Ally's world, as the Doctor only assumes that he does.