The Big Bang Theory spinoff Stuart Fails to Save the Universe is expanding its cast with more stars from the original show. News broke on Wednesday, August 13, that Ryan Cartwright, Josh Brener and Tommy Walker landed major recurring roles on the upcoming series. Cartwright, 44, was previously a student in class with Penny (Kaley Cuoco) on season 6 of The Big Bang Theory, while Brener, 40, was introduced as Stuart's (Kevin Sussman) friend and coworker. Walker, meanwhile, is new to The Big Bang Theory universe. He was cast as Gary, the handsome new boyfriend of Stuart's ex.