Can you believe The Big Bang Theory has already been on TV for 10 seasons?! We can't!
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The hit show's cast — including Kaley Cuoco, Jim Parsons, Johnny Galecki, and more! — have changed quite a lot since the sitcom premiered in 2007.
Click through the gallery below to see the stars then and now!
Kaley portrays Penny, the primary female character on the show. The actress has won a Satellite Award, a Critics' Choice Television Award and a People's Choice Award for the role!