Newhart will reprise his role as Sheldon's childhood hero Arthur Jeffries, aka Professor Proton, in the December 17 episode. The late Professor Proton will once again visit Sheldon (Jim Parsons) in his dreams as a ghostly Jedi to dispense advice and help him make a very important decision.
This will be Newhart's fourth appearance on the sitcom. He last appeared in Season 7's "The Proton Transmorgrification," in which Professor Proton died (on Star Wars Day no less) and appeared in Sheldon's dreams as Obi-Wan, promising to visit him again if he needed help. Newhart, 86, won his first-ever Emmy Award for his guest spot on the show in 2013.
The Big Bang Theory airs Thursdays at 8pm on CBS.