Knock knock knock. Penny?
“Our whole universe was in a hot, dense, state…” If you love the long-running CBS sitcom The Big Bang Theory, then you’ll recognize those to be the first few words of the show’s scientific, yet catchy, theme song. For 12 years, that song was a sign of comfort in our homes, as it indicated the beginning of another adventure with our favorite west coast scientists and the waitress that lived across the hall. The show follows roommates Leonard Hofstadter (Johnny Galecki) and Sheldon Cooper (Jim Parsons), two science-obsessed buddies whose lives are forever changed once Penny (Kaley Cuoco), a beautiful struggling actress and waitress at The Cheesecake Factory, moves in across the hall. Over the course of 280 episodes, the three of them, along with Leonard and Sheldon’s fellow scientist friends, Howard Wolowitz (Simon Helberg) and Raj Koothrappali (Kunal Nayyar), and in later seasons, Amy Farrah Fowler (Mayim Bialik) and Bernadette Rostenkowski (Melissa Rauch) got mixed up in hilarious situations. They bonded over their differences, developed new relationships, and supported each other as they grew in their respective careers. And they did all of this without an elevator, which might be their most impressive accomplishment.
Created by network television superstars Chuck Lorre and Bill Prady, the series was nominated for 55 Emmys, winning 10, including Jim Parsons for his performance as Sheldon. It also had a bevy of big-name guest stars over the years, including Laurie Metcalf, Bill Gates, Billy Bob Thornton, Stephen Hawking, James Earl Jones, and Carrie Fisher.
Here’s a list of the 15 best episodes of The Bang Theory.
“The Big Bran Hypothesis” (Season 1 Episode 2)
Penny asks Leonard if he could sign for her package delivery while she’s away at work and it ends up being the most exciting thing that’s happened to Leonard in a long time. Leonard is determined to play it cool and prove to Penny that he’s a man she could trust. After a long struggle pushing the furniture up the stairs, Sheldon can’t help but express his disgust at how messy Penny’s apartment is. Leonard’s worst nightmare becomes a reality when he catches Sheldon straightening up Penny’s apartment in the middle of the night with an oblivious Penny sleeping in the other room. Understandably, Penny is pretty freaked out when she sees what they did to her place without her permission. Leonard is an absolute wreck the entire episode as he tries to convince Penny that they aren’t two weirdos living across the hall from her. Though it takes some convincing, Penny realizes that Leonard and Sheldon, and their even more socially awkward friends, Raj and Howard, might not be all that bad. And, we learned that Sheldon organizes his cereal by fiber content.
“The Pancake Batter Anomaly” (Season 1 Episode 11)
Oh dear God, Sheldon is sick. Which means, everyone is sick…of him. Penny comes home from visiting her family in Nebraska and naively says that her trip was a real bummer because her whole family got some sort of flu. Upon hearing this, Sheldon immediately goes into overly cautious mode and reverts back to how he behaved when he had a cold as a child. Leonard, Raj, and Howard know by now that they must go as far away as possible from Sheldon when he gets sick. Penny, however, has no clue what she is in for. To escape the madness, Leonard, Raj, and Howard head to an all-day marathon of The Planet of the Apes movies. Meanwhile, Sheldon disrupts Penny’s shift at The Cheesecake Factory when he brings his whiney mood and mucus-filled tissues to the family restaurant. Out of options, “Typhoid Penny” leaves work to babysit Sheldon at his apartment. Though Penny is initially mad at Sheldon for causing a scene at her work, this episode serves as the beginning of what will blossom into an incredibly sweet friendship between the two of them. It’s also the debut of “Soft kitty, warm kitty,” the song Sheldon’s mother used to sing to him when he was sick with a cold. (Penny learned that the hard way.)
“The Barbarian Sublimation” Season 2 Episode 3
Penny’s really had it. She’s been in California for nearly two years and doesn’t have a single acting job to show for it, she’s in dire need of a raise at The Cheesecake Factory, and to top it all off, she tells a less-than-interested Sheldon that she hasn’t slept with anyone in 6 months. And now, her car key is stuck in her apartment door. Sheldon reluctantly lets Penny stay in his apartment while he plays online video games. Much to Leonard’s surprise, Penny becomes completely sucked into the world of multiplayer gaming and starts to neglect all of her responsibilities. By the second half of the episode, Penny is chugging Red Bulls, wiping Cheeto dust on her shirt, and furiously clicking away on her keyboard. It’s Penny like you’ve never seen her before.
“The Adhesive Duck Deficiency” Season 3 Episode 8
Leonard, Raj, and Howard head out to the desert to watch a meteor shower while Sheldon stays home to finish an important paper. His plans are derailed, however, when Penny slips in the shower and dislocates her shoulder. While waiting for the meteors, Howard gives the guys cookies he got from two women camping nearby. What they don’t realize is that the cookies are filled with pot. Raj, Leonard, and Howard end up on an accidental drug trip and miss the very thing they went to the desert for in the first place. This episode features one of the best Sheldon-Penny moments in the series when Sheldon accidentally grabs her boob when he tries to help her get dressed. By the end of the episode, a drugged-up Penny returns home and makes Sheldon sing “Soft Kitty” with her. It’s a duet you won’t forget.
Season 3 Episode 11: “The Maternal Congruence”
Merry Isaac Newton-mas! Nothing squashes the Christmas spirit quite as fast as a visit from Leonard’s extremely academic and emotionally unavailable mother, Dr. Beverly Hofstadter (Christine Baranski). Hearing she is coming to town puts Leonard in a state of fear and Sheldon in a state of joy. (After all, she’s kind of like a female Sheldon.) On top of that, Leonard didn’t tell Penny she was visiting because he knows that his mother (who’s a successful doctor) will disapprove of her son dating a waitress rather than some sort of science genius. In a night of unexpected mayhem, Penny gets drunk with the uptight Beverly and unleashes a side of the doctor that Penny didn’t know existed. Not only does Beverly approve of Penny dating Leonard by the end, but she considers Penny her “home girl.” Fa la la la la.
Season 3 Episode 16: “The Excelsior Acquisition”
Sheldon behind bars? A shirt that plays music? Comic book legend, Stan Lee? A lot happens in this marvelous episode. The boys are ecstatic when comic book shop owner, Stuart, tells them that Stan Lee is set to make an in-person appearance. At the same time, Sheldon receives a court summons for running a red light on November 16th. Wait a minute, Sheldon doesn’t have his driver’s license. How could this be? Well, that was the day Penny dislocated her shoulder and made Sheldon drive her to the hospital. So, while Raj, Leonard, and Howard meet their hero, Sheldon is stuck in court and quickly thrown in jail when he refuses to cooperate. (Oh, Sheldon.) Penny figures out Lee’s home address and takes Sheldon right to his front door. Stan Lee’s cameo does not disappoint, as he answers the door in a Fantastic Four-themed robe. Excelsior!
Season 4 Episode 8: “21-Second Excitation”
If you’re looking for a way to make your girls’ night very uncomfortable, invite Amy. In this episode, Leonard, Raj, Howard, and Sheldon camp out outside a movie theater to see an extended version of Raiders Of The Lost Ark (extended by 21 seconds, that is). Amy overhears that Penny is having her co-worker, Bernadette, over for a girls’ night and immediately feels left out. It’s important to note that. at this point in the series, Amy’s only been in a handful of episodes, so she has yet to develop a more relaxed rapport with the group that’ll be apparent in seasons to come. And that’s exactly what makes this night extra funny. Watching Amy try to assimilate and do “girl talk” is equal parts hilarious and frightening. At the movies, Sheldon crosses paths with his celebrity nemesis Will Wheaton (playing a version of himself) who uses his Star Trek street cred to cut the line.
Season 4 Episode 11: (“The Justice League”)
After her breakup with Leonard, Penny gets back together with her ex-boyfriend, the dumb and loveable Zack (Brian Thomas Smith). As a way of apologizing (in addition to the Milk Duds), the guys invite Zack along to the comic book store. While Zack beefs up his Archie collection, Sheldon has the idea of asking Zack to play Superman at the comic book store New Year’s Eve party because Zack has what the others lack: muscles. The Justice League of America was about to get slightly more realistic. Penny also realizes that she might still have feelings for Leonard. And remember, there’s no “I” in “Justice League”. Wait…
Season 5 Episode 17: “The Rothman Disintegration”
Amy takes her friend-crush on Penny to a whole new level in this episode. As a token of gratitude for all the ways Penny has helped her be less socially awkward and stiff, Amy gets a massive painting made of the two of them for Penny’s apartment. Penny is understandably horrified but hangs the painting up so she doesn’t hurt Amy’s feelings. At the university, Sheldon and his work-nemesis, Kripke (John Ross Bowie), argue over who’s getting the newly vacant big office. In order to decide who wins fair and square, the two battle it out in an area they are both equally bad at: sports. Watching those two men try to get a basketball in a hoop will brighten your day, guaranteed.
Season 5 Episode 18: “The Werewolf Transformation”
Uh-oh. Sheldon’s got bongos. When Sheldon’s barber ends up in the hospital, Sheldon has to face the harsh reality that his hair schedule is going to be totally out of whack. Even though his barber’s nephew, and even Penny, offer to cut his hair, Sheldon refuses. Amy, Penny, and Leonard convince Sheldon to use this opportunity to try out a less-regimented lifestyle. Sheldon’s decision to “embrace the chaos” and live freely cramps everyone’s style as they have to adjust to their long-haired, bongo-playing friend’s new demeanor. At the same time, Howard’s video chats with Bernadette get progressively scattered as he gets further along in his intense astronaut training. If Howard learned one thing, it’s that he should’ve packed more underwear.
Season 6 Episode 18: “The Contractual Obligation Implementation”
The Big Bang Gang is very busy this episode. Leonard, Howard, and Sheldon have to fulfill their contractual obligation to serve on a university committee, and Leonard encourages them to join him in promoting young women to pursue the sciences. The three end up giving what they hoped would be inspirational talks at Howard’s old middle school, but it ends up being a cringey disaster. Raj crashes girls’ night with Penny, Amy, and Bernadette in order to score some ideas on how to go on a date with the overly anxious Lucy (Kate Micucci). After suggesting Raj go to Disneyland, the three girls decide that they should skip work and spend the day there themselves. Raj ends up having a texting date with Lucy at the library while Amy, Bernadette, and Penny get princess makeovers, as Bernadette clearly threatens explains that there can only be one Cinderella…
Season 6 Episode 22: “The Proton Resurgence”
At long last, Sheldon is able to meet his childhood hero. Television and comedy legend, Bob Newhart, brings his deadpan charm to this episode as Professor Proton, the host of Sheldon and Leonard’s favorite science show growing up. Professor Proton thinks he was hired to teach science to a group of children but quickly realizes the children are Leonard, Sheldon, and Penny. Meanwhile, Raj asks Howard and Bernadette to babysit Cinnamon, his dog and most prized possession. Just when Howard and Bernadette think they nailed being “parents” for the day, they realize they left Cinnamon at the dog park. This episode begs the question: How the heck do potato clocks even work?
Season 7 Episode 3: “The Scavenger Vortex”
Poor Raj. No one came to his murder mystery dinner. But, perhaps there will be interest in a scavenger hunt? The gang goes all in for Raj’s elaborate scavenger hunt that takes them all over town. What makes this episode especially great is that we see the friends pair off with members of the group that usually don’t hang out with one-on-one, making it a refreshing change of pace. Bernadette’s feisty and aggressive personality triggers Leonard’s asthma, Sheldon’s book smarts pairs with Penny’s street smarts, and Howard and Amy realize they have a mutual love for Neil Diamond.
Season 7 Episode 15: “The Locomotive Manipulation”
It’s Valentine’s Day, and to celebrate, Amy booked her and Sheldon a romantic getaway. Amy knew that Sheldon wouldn’t be too keen on a bed and breakfast with strangers, so she made sure to invite Howard and Bernadette along on their Napa Valley train ride. Amy had high hopes that this trip would bring her and Sheldon closer, but initially, it does the opposite. Sheldon quickly falls under the spell of Eric (Eric Petersen), a fellow passenger with an encyclopedic knowledge of all things locomotives. Back at home, Penny and Leonard are tasked with babysitting Raj’s dog, Cinnamon, and end up at the vet when the dog accidentally eats chocolate. Tired of being ignored on the trip that she planned, Amy finally tells Sheldon how she really feels about his immature behavior. His response? A kiss! This was a surprise and a huge step forward for both of them. Also, don’t worry, Cinnamon is fine. And so is Raj, he got the vet’s number.
Season 12 Episode 24: “The Stockholm Syndrome”
It’s an incredibly daunting task to wrap up such a long-running and beloved series, but this series finale sent the show out with a bang. Sheldon and Amy fly out the crew to Scandinavia to accompany them while they accept the Nobel Peace Prize in Physics for discovering Super Asymmetry (whatever that means exactly). It’s not just Sheldon and Amy who have some jitters going into this big event. Howard and Bernadette have never been this far away from their children before, Raj has separation anxiety from his Cinnamon, and Penny and Leonard are doing their best to keep their pregnancy a secret so as to not take away from their friends’ big day. On the trip, however, Sheldon is even more, well, Sheldon, than he normally is, and the crew grows resentful and regrets going out of their way to support him. Though they consider leaving, the crew stays to support Amy and a selfish Sheldon. To everyone’s surprise, Sheldon scraps his self-absorbed acceptance speech to speak from the heart and detail how much each of his friends mean to him. For 12 years, these people developed not only strong relationships with each other, but also with their loyal viewers. The show ends where most of their memories began: eating Chinese food in the living room. “And it all started with a big bang, hey!” Oh, and the elevator is fixed!
All episodes of The Big Bang Theory are available to stream on HBO
