Meet Penny's brother and mother in season 10 of 'The Big Bang Theory'

Actress Katey Sagal is joining the cast of American sitcom The Big Bang Theory as Penny's mother.

The writers made the announcement of the news at San Diego Comic-Con, reported Us magazine.

The team disclosed that 62-year-old Sagal will appear in the season 10 premiere this year as Susan, who lives in Omaha, Nebraska, and thus has never appeared on the show.

Kaley Cuoco, who plays Penny, and Sagal earlier worked together in the sitcom 8 Simple Rules for Dating My Teenage Daughter, as mother-daughter.

Also appearing for the first time in the season 10 premiere will be Penny's brother, Randall, played by Jack McBrayer.

Randall is a drug dealer and has been released from prison in time to attend Leonard (Johnny Galecki) and Penny's redo wedding ceremony.