Tonight, it falls to Q2 and the fabric of the American sitcom The Big Bang Theory, and After twelve seasons, there will also be an end to the adventures of, among others, Penny and Leonard. In the slotaflevering is Sarah Michelle Gellar, known for o for a while.a. Buffy The Vampire Slayer, and a special guest. The Big Bang Theory, began in september of 2007. The series revolves around a group of scientists from the comics, games and sci-fi love.