An invention brings together Rajesh , front left, Leonard , rear left, Howard and Sheldon in Monday’s episode of CBS’ ‘The Big Bang Theory.’ CBS Monday announced a two-year renewal for TV’s most-watched scripted show, The Big Bang Theory, after most of the cast members, led by Johnny Galecki, Jim Parsons and Kaley Cuoco, who have signed on for upcoming 11th and 12th seasons.