The actor will appear in the October 26 episode, "The Helium Insufficiency", which sees Sheldon and Leonard forced to turn to a shady chemical dealer (Rapaport) to secure quantities of the rare gas helium on the black market because of a worldwide shortage.

Possibly Related Stories

Sheldon and Amy will take their relationship to the next level in a December episode, showrunner Steve Molaro confirmed after a taping on Tuesday. The pair, whose relationship has been on hold so far this season, will reportedly get intimate in the December 17 episode. Read the full story

CBS has released the synopsis for the ninth season finale of The Big Bang Theory, "The Convergence Convergence", which airs next Thursday, May 12. Judd Hirsch (Taxi) guest stars as Alfred, Leonard's father. Christine Baranski and Laurie Metcalf reprise their roles as Dr. Beverly Hofstadter and Mary Cooper, respectively, in the episode. Read the full story

CBS has issued the press release for the May 5 episode of The Big Bang Theory, "The Line Subsitititon Solution", the penultimate episode of season 9. Christine Baranski reprises her role as Leonard's mother, Dr. Beverly Hofstadter, in the episode. Read the full story

CBS has issued the press release for the next episode of The Big Bang Theory, "The Fermentation Bifurcation", which airs this Thursday. Brian Thomas Smith reprises his role as Penny's ex-boyfriend, Zack. Read the full story