1. LeVar Burton (Himself, Season 2-Intermediate Documentary Filmmaking)
Oh, LeVar Burton. I put this at number one simply because it brings out the best Troy moments the show has ever had. His presence alone sends Troy into speechless shock, and a pair meltdowns that send this episode over the top. We get Troy screaming in the break room, I told Pierce I only wanted a picture. You cant disappoint a picture!. And, of course, a fetal Troy in the restroom, singing the Reading Rainbow theme song, before completely losing it once again. (Set phasers to love me!) And a wonderful closer in the tag, as Troy and LeVar sit at dinner in the study room. Troy runs off screaming once again, leaving Mr. Burton alone at the table to say to himself, More fish for Kunta.
Honorable Mention: Luis Guzman (himself, Documentary Filmmaking:Redux) Katharine McPhee (Pierces stepdaughter Amber, Basic Genealogy)