<Li> Josh Wolowitz (Matt Bennett): Howard's half brother . </Li> <Li> Theodore (Christopher Lloyd): Sheldon rented out his room to Theodore in "The Property Division Collision". </Li> <Li> Denise (Lauren Lapkus): An employee working at Stuart's comic book store with an amazing knowledge of comic books and becomes Stuart's girlfriend . </Li> <Li> George "Georgie" Cooper Jr . (Jerry O'Connell): Sheldon and Missy's brother, who lives in Texas and runs a car tire business . Often at odds while growing up, the Cooper brothers begin to reconcile their differences when Sheldon and Leonard visit George in season 11 before Sheldon's wedding . Known as Georgie in his younger days, he appears as a main character on Young Sheldon played by Montana Jordan . </Li>

Who plays stewart's girlfriend on big bang