The Big Bang Theory: The Celebration Experimentation

The 200th episode of The Big Bang Theory, titled "The Celebration Experimentation," airs tonight on CBS! The gang celebrates Sheldon's big day with some friendly faces. Happy Birthday Sheldon!

After more than nine years together, the gang finally celebrates Sheldon's birthday, surprising him with a few special guests, including Christine Baranski, Sara Gilbert, Wil Wheaton and Batman's Adam West.

Check out clips and a promo for the episode in the videos below.

The Big Bang Theory airs its 200th episode tonight at 8/7c on CBS.