Big Bang Theory Scoop: Details on James Earl Jones and Carrie Fisher's Guest Roles

James Earl Jones and Carrie Fisher will both guest-star in an upcoming episode of The Big Bang Theory, TVGuide.com has confirmed.

As first reported by TVLine.com, the Star Warsalums — who played Darth Vader and played Princess Leia, respectively — will cameo as themselves on the CBS series. But why exactly will they cross paths with Sheldon (Jim Parsons)?

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"For the first time, Sheldon and the guys are locked out of Comic-Con tickets and they don't get in," showrunner Steve Molaro tells us. "Leonard [Johnny Galecki], Wolowitz [Simon Helberg] and Koothrappali [Kunal Nayyar] are going to get scalped passes. Sheldon's solution is he is going to start his own comic book convention, he just needs one great panelist to make it happen. He realizes, through Twitter, where James Earl Jones is having sushi in Studio City and is going to confront him personally."

As for Fisher, Molaro would only tease, "She's got a very small, very funny, very weird part."

Jones and Fisher follow a long line of geek-tastic celebrities who have made their way to Bang, including Stan Lee, George Takei, Katee Sackhoff, Leonard Nimoy, Wil Wheaton, Stephen Hawking and Summer Glau.

Are you excited for the Star Wars alums to appear?

The Big Bang Theory airs Thursdays at 8/7c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)