Comic-Con: 'Big Bang Theory' Casts Katey Sagal, Jack McBrayer

Prepare to meet some additional family members on CBS' The Big Bang Theory.

Producers behind the nerdy comedy announced Friday at Comic-Con that Sons of Anarchy's Katey Sagal will play Penny's (Kaley Cuoco) mother, Susan, and the series will also be introducing Penny's brother, Randall. Penny's brother will be played by 30 Rock grad Jack McBrayer, who made a surprise appearance to wrap Friday's panel. Both will appear in the season 10 premiere.

"Katey has played Kaley's mom before on 8 Simple Rules, and she told us she's always up for playing Kaley's mom," showrunner Steve Molaro said at the panel. Susan is described as stressed out and neurotic from a life with her troubled son.

Penny's brother has been referenced multiple times. He's said to have worked in a meth lab and been in prison. During the panel, moderator Melissa Rauch (Bernadette) asked him if he'd ever been to jail, with McBrayer joking, "Recreationally ... I look good in orange. I'm good at making new friends!" Randall is described as a cheerful former drug dealer and ex-con.

The casting news comes after the comedy, created by Chuck Lorre and Bill Prady, cast Taxi alum Judd Hirsch to play Leonard's (Johnny Galecki) father. He appeared in the season nine finale, which ended with a cliffhanger as his character Alfred, seemed to have spent the night with Sheldon's mother, played by Laurie Metcalf, in the season nine finale. Metcalf was recognized for her role with an Emmy nomination this year. Casey Sander has also recurred as Bernadette's father.

Howard's mother, meanwhile, was a staple on the series, though she never appeared on-screen. She was voiced by the late and great Carol Ann Susi.

Sagal's credits include ABC's upcoming Dirty Dancing, Pitch Perfect 2, Futurama and The Bastard Executioner. She's repped by WME. McBrayer, a five-time Emmy nominee, is repped by UTA.

Big Bang Theory returns Sept. 19 on CBS.

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