The ‘Big Bang Theory’ dropped the news of major TV reunion at their Comic-Con panel on Friday. The show announced that Katey Sagal would be guest starring on the show’s 10th series, playing the mother of Kaley Cuoco’s character Penny.

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Sagal and Cuoco have played mother and daughter before, for three seasons on ABC comedy ‘8 Simple Rules’. Sagal will play Penny’s mother Susan, who has never been seen before on the show.

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Susan will appear in the season 10 premiere as Penny and Leonard have their re-do wedding. Also showing up will be ’30 Rock’s’ Jack McBrayer, who will play Penny’s drug-dealing brother Randall, who has been released from prison in time to attend the wedding ceremony.

Posting a throwback pic of her and Sagal together on Instagram, Cuoco wrote: "Once my tv mom, always my tv mom love [email protected] !!!!! #fullcircle.” The show will return to CBS on September 19 at 8 p.m. 

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Speaking to Entertainment Tonight after the big announcement, Executive Producer Steve Molaro said: "There will be a little reunion there, which we're excited about. She’s going to be a little bit of a neurotic character because she's spent her life with her troubled son, Randall, who has been in and out of jail and has had some issues with dealing drugs. So we're going to start to dive into that."