Photos from The Big Bang Theory's Geekiest and Greatest Guest Stars!

Katey Sagal and Jack McBrayer's appearances made for a pretty star-studded season ten premiere. In the episode, Sagal brings things full circle by playing Penny's mom, Susan. Pretty cool, since she played Kaley Cuoco's mom on 8 Simple Rules. Meanwhile, McBrayer plays Penny's brother, Randall, who once was arrested for cooking meth.

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