When The Big Bang Theory first premiered in 2007, no one knew it would become the massive phenomenon that it is today. Nine seasons later, the CBS series remains one of the most popular and widely watched sitcoms on TV. With the ninth season now concluded, we decided to take a look back at some of our favorite episodes from the show’s run so far. While there are obviously a lot to choose from, these 12 episodes (listed in chronological order) are some of the biggest standouts, highlighting the best of Sheldon, Penny, Leonard and the rest of the gang.
1. “The Middle Earth Paradigm”
Season 1, Episode 6
The guys attend a Halloween party at Penny’s apartment dressed in exactly the kind of nerdy costumes you’d expect: Sheldon as the Doppler Effect, Leonard as Frodo, Raj as Thor, and Howard as Robin Hood. Needless to say, they don’t exactly fit in with Penny’s friends, making for a series of hysterically awkward encounters. By the end of the night, Leonard and Penny have shared their first kiss and Raj wakes up in bed with a random girl. The episode is the perfect showcase of what The Big Bang Theory is about, at least in early seasons: four nerdy guys trying desperately to fit in and sometimes, against all odds, actually succeeding.
2. “The Barbarian Sublimation”
Season 2, Episode 3
In this episode, Sheldon gets Penny hooked to the world of gaming by introducing her to the PC game, “Age of Conan.” Penny, sick of getting nowhere in her personal and professional life, quickly becomes addicted, forgoing hygiene and work to spend days playing, eating Cheetos, and bugging Sheldon for ways to get to the next level. It’s one of the best early examples of the funny and unexpectedly warm relationship between Sheldon and Penny (aka”Shenny”). Plus, Penny realizing that she has to snap out of it while talking to Howard makes for a hilarious moment.
3. “The Bath Item Gift Hypothesis”
Season 2, Episode 11
It’s Christmas time and after finding out that Penny has gotten him a gift, Sheldon finds himself forced to reciprocate the gesture. Without knowing exactly how much she’s spent on him, he can’t make up his mind and ends up buying a bunch of gift baskets to cover his bases. When it comes time to actually exchange gifts, Penny presents him with something beyond his wildest dreams: a napkin used and signed by Star Trek’s Leonard Nimoy. Cue a hilarious Sheldon-sized freakout that results in the rarest of occurrences: a hug from Sheldon to Penny.
4. “The Einstein Approximation”
Season 3, Episode 14
In this episode, Sheldon is once again grappling with a puzzle he can’t solve – specifically, a physics problem about electron behavior. After enduring sleepless nights and going to all kinds of crazy lengths to try to find an answer, he decides he needs to take on a menial job that will allow him to free up his mind. He ends up masquerading as a waiter at the Cheesecake Factory where Penny works, where he finally gets his answer.
But the true highlight of the episode? When Leonard gets a call in the middle of the night that he has to pick Sheldon up at a local mall, where he is using the plastic balls in a children’s ball pit to build carbon atoms. As Leonard desperately tries to get him out of the pit so they can go home, Sheldon keeps diving in and popping out of the balls, shouting “Bazinga!”
5. “The Cruciferous Vegetable Amplification”
Season 4, Episode 2
When Sheldon works out that he won’t live long enough to download his consciousness into a robot body, he attempts to extend his lifespan by changing his diet and eating cruciferous vegetables. When those only serve to give him gas, he instead decides to build a “Mobile Virtual Presence Device,” which leads to countless funny moments. Case in point? Leonard trying to turn off Sheldon while driving his virtual presence to work and Sheldon trying to figure out how to open his office door, considering his device has no hands. Major bonus: Apple co-founder Steve Wozniak appears in one of the show’s best cameos.