Author Sue Grafton, known for her "alphabet" series of mystery novels ("O Is For Outlaw", "B Is For Burglar", etc.), now has a definite televersion of herself in Toobworld. She was at a book-signing in Scranton, Pa., about which Phyllis Vance told her boss Michael Scott. He sent her from 'The Office' to cajole Ms. Grafton into appearing in their "Local Ad" for the Dunder-Mifflin paper company.
Ms. Grafton didn't actually appear in the episode (and she refused to appear in their commercial). But even though Phyllis' interactions with her happened off-camera, she still exists in Toobworld.
Some other real world authors who have established televersions:
Anne Rice - 'Ellen'
'Stephen King' - 'The Simpsons'
Thomas Pynchon - 'The Simpsons', 'The John Larroquette Show'
Kurt Vonnegut - commercials for TIAA-CREF, Nissan Murano, Discover credit card
William Gibson - 'Wild Palms' (and looking very well preserved in the near future)
Alex Haley - 'Roots: The Next Generation' (although he was portrayed by James Earl Jones)