Two Degrees of Separation (from me) by PotatoD

Question 6

Brian Greene, a theoretical physicist well-known for his scientific books for general audiences and related TV appearances (including one appearing as himself on a hit sitcom), was in my college class. I never met him, but, hey, I'm making the rules here, and I say that makes me two degrees of separation from this actor, identified by Forbes Magazine as the top-paid prime time TV actor of 2015. Name the actor.

Jim Parsons