Can you believe The Big Bang Theory has already been on TV for 10 seasons?! We can't!
MUST SEE: It's a Girl! The Big Bang Theory Baby Is Here — Find out Her Name!
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!
1 of 8
Kaley Cuoco (Penny Hofstadter)
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!
2 of 8
Jim Parsons (Sheldon Cooper)
Jim has won four Primetime Emmy Awards and a Golden Globe for his portrayal of theoretical physicist Sheldon!
3 of 8
Johnny Galecki (Leonard Hofstadter)
Johnny has been playing experimental physicist Leonard since the show's start in 2007!
4 of 8
Simon Helberg (Howard Wolowitz)
Simon won a 2013 Critics' Choice Television Award for playing engineer Howard.
5 of 8
Kunal Nayyar (Rajesh Koothrappali)
Kunal was one of the world's highest paid TV actors of 2015 due to his role on Big Bang — so cool!
6 of 8
Melissa Rauch (Bernadette Rostenkowski-Wolowitz)
Melissa joined the show as a guest star for Season 3 in 2009 and became a cast regular in Season 4!
7 of 8
Mayim Bialik (Amy Farrah Fowler)
In addition to acting, Mayim also has a PhD in Neuroscience — just like her Big Bang character, Amy!
8 of 8