’TBBT’ Recap & Spoilers S09E17: Sheldon Celebrates His Birthday on 200 Episode -- with Batman!

For its milestone 200th episode, The Big Bang Theory celebrated its most popular character, Sheldon Cooper, as the regular cast and some of everyone's favorite recurring characters visited him for his birthday in the latest spoilers. Season 9, Episode 17 was a sweet and simple episode, revolving entirely around Sheldon -- including the original live-action Batman, Adam West, as shown in this recap!

As fans of the show have known for a while, Sheldon (Jim Parsons, who has won four Emmys and a Golden Globe for the role) doesn't really like to celebrate his birthday. As his latest one comes up, his girlfriend Amy (Mayim Bialik) convinces him to let her and their friends throw a party, to which he reluctantly agrees, though he does it under protest.

We also discover the reason Sheldon doesn't like to celebrate his birthday: when he was a little boy he always shared a party with his twin sister, Missy, and she always had a lot of guests while he didn't have friends growing up.

Ahead of the big party, Leonard, Raj and Howard (Johnny Galecki, Kunal Nayyar and Simon Helberg) decide to fulfill Sheldon's dream and have Batman and his birthday party, so they hire West, who played the Caped Crusader in the 1960s series, to show up. Of course, having a Batman on board also means one thing: a lot of discussions over who's played the DC superhero the best.

For Raj, Michael Keaton was the best and Christian Bale is vastly overrated, but West doesn't mind doing his own list, obviously topped by himself and with "pretty boy [George] Clooney" at the bottom. Will Arnett's Lego Batman from The Lego Movie is also included, FYI.

The whole gang is there to celebrate another year in Sheldon's life, including pregnant Bernadette (Melissa Rauch), who helped Amy and Penny (Kaley Cuoco) organize the bash at Sheldon and Leonard's apartment.

As for the recurring characters, former Sheldon nemesis Wil Wheaton and Leslie Winkle (Sara Gilbert) were around, plus the hilarious and awful Barry Kripke (John Ross Bowie) and Stuart (Kevin Sussman), who takes a moment (or a few) for self-pity when he realizes everyone but him knew Bernadette was having a baby.

Leonard's mom and Sheldon's friend, Beverly Hofstadter (the ever-brilliant Christine Baranski) also dropped by for his birthday, and it was revealed she'd had a 60th birthday party that Sheldon was invited to but Leonard wasn't, though both his siblings were. In a hilarious subplot throughout the entire episode, Kripke hits on Beverly, even calling her a cougar, to Leonard's dismay.

Once Sheldon gets to the party, he becomes overwhelmed: so many people who love him (and "Adam West for some reason") have showed up for his birthday that he gets a little choked up, remembering all the awful birthdays he had growing up -- so he locks himself in the bathroom.

Penny follows him there (she knows he's not doing anything bathroom-related because he sends her the schedules for his weekly bowel movements) and sweetly talks to the neurotic physicist. While he apologizes for his behavior, he says he doesn't really know how to handle that kind of affection, and she says that's all right and that, if he prefers to stay in the bathroom all night she'll join him because he's one of her "favorite people."

Eventually, Sheldon agrees to come out to the party, thanks everybody for showing up and demands people to toast for him. Everyone's words are very sweet, including how Leonard calls him a "brother" and Amy says she's thankful he was born.

The biggest moment of the bash, however, comes just as the episode nears its end: Sheldon receives a Skype call from fellow theoretical physicist and "Words with Friends" rival Stephen Hawking, who attempts to sing "Happy birthday" to him but, seeing as he can't sing, the whole thing is hilarious.

"The Celebration Experiment" episode ends with a sweet "Happy birthday" song from all those who love Sheldon, with a 2-second delay from Hawking.