These Before And After Pics Of "The Big Bang Theory" Cast Show Just How Much Has Changed On The Series

    12 years later...

    After 12 long years, The Big Bang Theory is coming to an end, making it the longest-running multi-camera sitcom in TV history.

    In honor of the series finale, here's a look back at the cast:

    Kaley Cuoco as Penny

    Jim Parsons as Sheldon Cooper

    Johnny Galecki as Leonard Hofstadter

    Kunal Nayyar as Rajesh Koothrappali

    Simon Helberg as Howard Wolowitz

    Melissa Rauch as Bernadette Rostenkowski-Wolowitz

    Mayim Bialik as Amy Farrah Fowler

    The end of an era!!