"The Big Bang Theory" is undeniably one of the most popular shows currently, and it is not surprising the CBS show is going to air its 200th episode Thursday, Feb. 25, 2016. Season 9 Episode 17, titled "The Celebration Experimentation", will use the guise of Sheldon's (Jim Parsons) birthday to celebrate the big day on screen and bring back many beloved guest stars.

It is understood that Leonard's (Johnny Galecki) cold and distant mother Dr Beverly Hofstadter (Christine Baranski) will attend Sheldon's birthday party. As fans know, she has connected more with Sheldon than Leonard, and the two shares contempt for Leonard and his accomplishments.

Also returning to celebrate the 200th episode are Leslie Winkle (Sara Gilbert) and Will Wheaton, who used to Sheldon's nemeses. Sara Gilbert was part of the main cast previously, and even had a romantic storyline with Leonard.

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Even Adam West, the star of the 1960s' "Batman" series, will put in an appearance in the special episode. And like Will Wheaton, he will portraying himself in "TBBT".

Considering it is Sheldon's big day, Amy (Mayim Bialik) will be hoping for some under-the-sheet action with her boyfriend. However, the birthday boy seems to be as clueless as ever. In the promo, when Amy tells him: "May be later, I will get to see you in your birthday suit", Sheldon replies: "This is my birthday suit," pointing at this attire.

However, Sheldon has come a long way since the first season, and is even seen giving Penny (Kaley Cuoco) a huge bear hug. The old Sheldon would never have even touched Penny's bare hands for a shake.

Watch Season 9 Episode 17 of "The Big Bang Theory" at 8 p.m. (EST) Thursday, Feb. 25, 2016. You can also live-stream "The Celebration Experimentation" via CBS Live.