Since its 2007 debut, The Big Bang Theory has evolved into an ever-expanding franchise. The small-screen success resulted in two prequel series, Young Sheldon and Georgie & Mandy’s First Marriage. The former follows the story of quirky genius Sheldon Cooper navigating the world as a teenager, while the latter is its direct sequel that looks at Sheldon’s older brother Georgie and the first (of many) marriages referenced in the original sitcom. Currently, there’s also another untitled sequel spin-off in the works.