'The Big Bang Theory' Episode 200, Who Guest Stars with Caltech Guys?

It's been nine years since the first time CBS showed us a sneak peek into the world of four Caltech scientists and a hot neighbor, introducing Jim Parson's Sheldon, Johnny Galecki's Leonard, Simon Helberg's Wolowitz, Kunal Nayyar's Raj and Kaley Cuoco's Penny. Now, The Big Bang Theory celebrates its 200th episode and the geek-themed show gets a few more guest stars!

The milestone 200th episode, entitled "The Celebration Experimentation," will take place during Sheldon Cooper's birthday, giving the cast a fictional reason to celebrate their real-life major achievement. The whole current cast of the show, including Mayim Bialik and Melissa Rauch, will of course be part of the episode, but someone else will be stepping in: Batman!

As previously reported, Adam West, who famously played the Caped Crusader in the iconic '60s show Batman, will be dropping by Sheldon's birthday celebrations this Thursday.

TBBT showrunner Steven Molaro told TV Guide that they'd approached West to drop by the show for years, but it was a great move that they actually managed to get him this time around for such an important episode. Let's expect Sheldon to compare him to the likes of Christian Bale and most recently Ben Affleck, and things are bound to get a little uncomfortable for the characters.

Besides West, a few actors will be coming back for the big episode, including Wil Wheaton (in his recurring role as a fictionalized version of himself), Sara Gilbert (Leslie Winkle), John Ross Bowie (Kripke) and Christine Baranski as Leonard's very Sheldon-like mother.

Details of the episode are being kept secret to fans, so beyond the fact that Sheldon will be celebrating a birthday alongside Batman, it's anyone's guess what will happen -- but the combination of some of the show's funniest supporting characters should make for an amazing experience!

Tune in to the 200th episode of The Big Bang Theory tonight on CBS!