30 of the most-memorable moments from ‘The Big Bang Theory’

The series has had plenty of memorable moments. Sonja Flemming/CBS
  • “The Big Bang Theory” is ending after more than a decade on air.
  • It’s had plenty of memorable moments.
  • Penny and Leonard’s engagement was definitely one.
  • Sheldon and Amy’s wedding was another.
  • This post contains spoilers from “The Big Bang Theory.”
  • Visit INSIDER’s homepage for more stories.

On Thursday, May 16, millions of fans will finally say goodbye forever to smash-hit CBS sitcom “The Big Bang Theory.”

For more than 12 years and 276 episodes, Sheldon, Leonard, Howard, Raj, Amy, Bernadette, and Penny brought smiles to our faces with their unapologetically nerdy banter, love for one another, and of course, the bazingas.

To prepare you for the upcoming series finale, INSIDER compiled a list of Big Bang Theory’s best scenes over the past 12 years.

Check out our roundup below to revisit some of the show’s most-memorable moments:

When Penny kissed Leonard for the first time.

This happened during “The Middle Earth Paradigm.” CBS

After watching her jock ex-boyfriend nearly get into a fight with Leonard at her Halloween party, Penny heads over to the latter’s apartment and kisses him for the first time. It’s the kiss that set up the beginning of their will-they-won’t-they dynamic and helped to establish them as the show’s OG couple.

When the guys went to their first party at Penny’s.

This also happened during “The Middle Earth Paradigm.” CBS

If you’re looking for a scene that illustrates the essence of all the guys’ in the earlier seasons, look no further than that first Halloween party at Penny’s apartment in season one.

Between Sheldon getting frustrated at the party guests inability to guess his Doppler effect costume and Leonard yelling “That’s how we do it in the Shire!” in his Frodo costume after kissing Penny, this season one episode showed viewers that the characters’ unapologetic nerdiness would define the show.

When the “soft kitty” song became a thing.

This happened during “The Pancake Batter Anomaly.” CBS

Of all the recurring bits on the show, few are sure to make you melt the way the “Soft Kitty” does. Viewers are first introduced to the lullaby when a bedridden Sheldon asks a hesitant Penny to sing it to him. She agrees after learning that Sheldon’s mother used to sing it to him every time he was sick.The moment brings the two closer together and lays the foundation for their unique friendship dynamic that would continue for the next eleven seasons. Throughout the remainder of series, the two occasionally sang the song to each other, and one point, Leonard and Penny even sang it to a sleeping Sheldon.

When the gang found out the power of liquid courage on Raj.

This happened during “The Grasshopper Experiment.” CBS

One of the defining characteristics of Dr. Rajesh Koothrappali during the first half of the series was his inability to speak to women. But when Penny practices her bartending skills on the guys and hands him a drink, it suddenly works magic on his social skills.

When Penny gave Sheldon the best gift.

This happens during “The Bath Item Gift Hypothesis.” CBS

Thanks to Sheldon’s compulsive need to ensure gift exchanges are even, he buys a series of generic baskets at varied price points to give to Penny for the holidays. Since he anticipates her gift to him will be a superficial and meaningless he believes this is the only acceptable way to return the gesture.

Of course, Sheldon soon realises he underestimated how well his neighbour knows him. When he opens the gift box and finds a tissue that was one used by his hero, a.k.a “Star Trek” legend Leonard Nimoy, he is stunned. The result? He decides to give Penny literally every basket he bought.

When Penny punched Sheldon.

This happens during “The Precious Fragmentation.” CBS

If you needed a reminder that the guys love Lord of The Rings (Leonard did dress as a Hobbit during the first Halloween episode) this was it. After the group comes upon an actual ring that was used in the Lord of the Rings movies, each guy becomes determined to be the sole owner. As expected, tricks, deception, and near chaos ensues.

But once Penny uppercuts Sheldon in the mouth for sneaking up on her in her sleep, it becomes clear this game involves no funny business.

When Sheldon and Penny met Stan Lee at his house.

This happens during “The Excelsior Acquisition.” CBS

“The Big Bang Theory” has been well lauded for its memorable roster of guest stars over the years, including Judy Greer, Steve Yeun, Stephen Hawking, Neil Degrasse Tyson, and more. But if there’s one celebrity cameo that’s to be cherished forever, it’s the appearance of the late comic book legend Stan Lee way back in season three.

During this episode, Sheldon scrambles to get out of court so he can meet the esteemed Marvel comics creator at Stuart’s comic book shop. When his plan fails, he and Penny decide to show up at his house, and Sheldon incorrectly reads social cues and invites himself inside.

When Sheldon gave a drunk speech in front of all of his colleagues.

This happens during “The Pants Alternative.” CBS

When Sheldon enlists his friends to help him give a proper speech upon accepting The Chancellor’s Award for Science, nothing works. Instead, he takes Penny’s last-minute advice of turning to liquid courage but doesn’t quite know his limit. What follows is a hilariously cringe-worthy speech packed with bad science jokes, a periodic table song, and Sheldon de-pantsing himself on camera.

When Raj gave Howard the funniest best man toast ever.

This happens during “The Stag Convergence.” CBS

Speaking of embarrassing drunk speeches, if it’s going to be passionate, you better believe it’s from Rajesh. Despite Howard’s protests, a drunk Raj loudly tells stories about his best friend’s awkward encounters before reminding everyone of his love for his best friend. The scene also features more memorable drunk Sheldon lines, making it the perfect mix of messy and downright hilarious.

When viewers first met Amy.

This happens during “The Lunar Excitation.” CBS

For the first three seasons, Sheldon Cooper was once thought of as someone who would never in a million years be compatible with another human being. So when Howard and Raj decide to set Sheldon up on a date for their own amusement, they think they’re in for a hilarious evening.Of course, the joke’s on them when it turns out Amy Farrah Fowler hits it off with Sheldon immediately, displaying similar idiosyncrasies and aversion to social convention. Cue Howard saying to Raj in total disbelief, “What have we done?”

When Sheldon’s mum used reverse psychology on him.

This happens during “The Zazzy Substitution.” CBS

One of the most beloved recurring characters throughout the series was the mother of Dr. Sheldon Cooper (portrayed by the ever talented Laurie Metcalf.) Despite her son being a super genius, Mrs. Cooper proves that she is still more than capable of outsmarting him. In this moment, she convinces Sheldon to start dating Amy again by using reverse psychology and telling him that Amy is not the right match for him.

Since Sheldon is the type to not back down from a challenge (or opportunity to prove someone wrong), it works. The scene is a fun reminder that mothers do know what’s best.

When Sheldon attempted to make himself into a robot.

This happens during “The Cruciferous Vegetable Amplification.” CBS

Even super-genius Sheldon had his limitations. During this episode, the theoretical physicist decided to eschew physical interaction with the outside world and instead experiment with living his life entirely through a screen from the comfort of his bedroom.

The episode unfolds into absolute silliness as robot Sheldon (which was basically a tablet attached to a moving robot wearing a tee shirt) sits in the passenger seat of Leonard’s car and later wheels around his office, taunting Leonard for doubting his experiment.

When Amy and Leonard went to a wedding together.

This happens during “The Pulled Groin Extrapolation.” Richard Cartwright/CBS via Getty Images

This scene showed viewers that Amy was one of the most pleasant and open-minded characters of the group due to her willingness to loosen up and have a good time. During this short wedding scene, Amy encourages Leonard to break out of his shell and have fun by jokingly drawing a fake mustache on her finger and convincing him to dance.

The moment becomes a pivotal bonding moment for the characters and showed viewers how Amy’s silliness could bring out the best in people.

When Sheldon got into prank wars with the guys.

This happens during “The Good Guy Fluctuation.” Monty Brinton/CBS via Getty Images

Beyond their love for science, if there’s one thing that essentially defined the friendship between the guys and Sheldon, it’s their practical jokes. But of all those moments, Sheldon popping up from inside the couch and scaring the beejebus out of Leonard, while yelling, “Bazinga, punk! Now we’re even” deserves special recognition.

When Howard and the group serenaded Bernadette at the hospital.

This happened during “The Romance Resonance.” CBS

After a lab accident quarantines Bernie at the hospital, Howard decides to bring the romance to her by writing and performing a song for her behind the glass. The best part? He brings the rest of the group as backup singers, and despite Sheldon’s reluctance, everyone sings along.

When the ladies owned the guys at all the games.

This happened during “The Re-Entry Minimization.” CBS

All it took was Sheldon losing a battle of Pictionary for him and Leonard to challenge the ladies to an epic Battle of the Sexes game night featuring wrestling, dizzy long division, and a pie eating contest.

When the guys got dressed up in their Star Trek best.

This happens during “The Bakersfield Expedition.” Monty Brinton/CBS via Getty Images

Even though a lot of bad happened to the guys in this episode (such as getting their car and clothes stolen,) nothing beats seeing them all dressed up in full cosplay trying to navigate through the desert.

When Penny finally told Leonard she loved him.

This happened during “The 43 Peculiarity.” CBS

Although it’s not ideal to hear someone say “I love you” for the first time during a heated argument, Penny’s words to Leonard came off as so natural, it’s hard to deny they’re anything but sincere. Given that the couple was far from perfect from the beginning and still managed to make it through, it makes sense that this kind of intimacy would come out at the most unpredictable moment.

When the gang came together to help Howard move on from his past.

This happened during “The Closet Reconfiguration.” Monty Brinton/CBS via Getty Images

In one of the more touching moments of the series, the gang learns that Howard’s absent father actually wrote Howard a letter for his eighteenth birthday. However, Sheldon is the only person who ever got a chance to read the letter before Howard destroyed it. As a result, the gang thinks of different nice “what ifs” the letter could have said and tell Howard, asking him to guess which is the truth.

Viewers aren’t clued in to which statement is the truth at all, leaving them in limbo like Howard. Despite Howard telling the group he doesn’t ever want to know the truth, the scene is one of the best moments of the group coming together to support a friend in need.

When Howard and Amy bonded over Neil Diamond.

This happened during “The Scavenger Vortex.” CBS

Just when you thought two people had absolutely nothing in common, Neil Diamond proves otherwise. After being paired up for Raj’s scavenger hunt party, Amy and Howard discover their shared passion for the musician and decide to indulge in one of life’s greatest joys: car singalongs.

This becomes the defining feature of their friendship as they belt out “Sweet Caroline” in the car and many episodes later, take a “Neil Diamond break” during a work project.

When Sheldon kissed Amy for the first time.

This happened during “The Locomotive Manipulation.” CBS

In a moment that’s almost as sweet as his surprise proposal, Sheldon Cooper, a man who could not stomach holding hands, won hearts everywhere by suddenly kissing longtime girlfriend Amy Farrah Fowler during the 7th season.

This all happens after the latter reveals how disappointed she is with Sheldon’s unwillingness to spend time with her during their Valentine’s Day vacation. Naturally, in true Sheldon fashion, he responds by ranting about the silliness of romance and goes in for a quick smooch trying to prove a point. But to the delight of viewers, his peck turned into a much longer, meaningful kiss.

When Professor Proton’s passing got to Sheldon.

This happened during “The Proton Transmogrification.” CBS

In the “Big Bang” universe, Professor Proton was a children’s science television show host who served as a major role model for Sheldon and Leonard (but mostly Sheldon.) His death is one of the few things in the entire series that has a prominent emotional impact on Sheldon. Although it’s a sad moment, it causes him to embrace Leonard in a full hug, which previously would have been unheard of.

When the gang celebrated the prom they always wanted.

This happened during “The Prom Equivalency.” CBS

Even though the event didn’t go totally according to plan, it did feature slow dances, tuxedos, dresses, and lots of love.

When Leonard finally proposed to Penny with an actual ring.

This happened during “The Gorilla Dissolution.” CBS

One of the big running jokes on the show was Leonard and Penny’s back and forward marriage proposals that never happened at the right time. After three (or four) failed attempts at sealing an engagement, viewers finally got the satisfaction of seeing Leonard actually put a ring on it.

During this scene, Penny finally decides that getting married is a practical idea and Leonard catches her off guard by pulling out the actual ring that she had never seen before from his wallet. The element of surprise causes Penny to give him the obviously anticipated, yes, but more importantly, it turns an otherwise anticlimactic adult discussion into one of the series’ sweetest scenes.

When Sheldon and Amy got back together.

This happened during “The Earworm Reverberation.” CBS

After a heartbreaking season eight finale that ended with Amy breaking up with Sheldon, and a season nine that showed her attempting to move on, this reunion felt well-earned. In true Sheldon fashion, he interrupts her date by knocking on her door and declares his love for her. The scene ends in a lengthy smooch between the pair that cues Amy’s date to leave, but the two scientists to finally be where they belong – with each other.

When Leonard and Penny eloped in Vegas.

This happened during “The Matrimonial Momentum.” Sonja Flemming/CBS via Getty Images

Viewers breathed a sigh of relief after nine seasons of will-they-won’t-they finally got put to rest in a Las Vegas wedding chapel. The standout moment? After Leonard professes his love through thoughtful, poetic vows, Penny, unprepared, responds by reciting the lyrics to “You’ve got a Friend in Me.”

Naturally, an overly emotional Leonard responds by tearfully proclaiming that he loves “Toy Story.”

When Bernadette and Howard became parents on Amy’s birthday.

This happened during “The Birthday Synchronicity.” Monty Brinton/CBS via Getty Images

Baby Halley was immediately welcomed with lots of love by the group, despite interrupting Amy and Sheldon’s planned activities.

When Penny comforted Sheldon on his birthday.

This happened during “The Celebration Experimentation.” CBS

It’s hard not to love a good Penny and Sheldon moment. Although there have been plenty of them throughout the entire series, this one from season nine stands out because it revealed how much the characters had grown over the years.For one, Sheldon acknowledges to Penny that he does care about disappointing other people when he expresses worry about ruining his party. But once Penny responds by saying she’d stay with him all night in the bathroom if he wanted, it becomes clear these characters are more than just neighbours now – they’re family.

When Sheldon and Amy dressed up as Howard and Bernadette for Halloween.

This happened during “The Imitation Perturbation.” CBS

Throughout the series, there were a lot of great moments involving costumes, impressions, and practical jokes. For this reason, it’s perfectly fitting that during the last Halloween episode ever, viewers were treated with Howard nailing a perfect Sheldon Cooper costume. But the real treat came when Sheldon and Amy got their revenge by showing up to the party dressed as Howard and the other couple.

When Sheldon and Amy tried to do science on their wedding day.

This happened during “The Bow Tie Asymmetry.’ CBS

To no one’s surprise, Sheldon did not care about the social convention of not seeing the bride before the wedding. Moments before their wedding ceremony begins, he barges into her dressing room to share his recent scientific epiphany and insists on using her lipstick to write equations on the mirror.

It became a classic Big Bang Theory moment as the pair become so entrenched in the problem that they nearly forget about the ceremony until Leonard and Penny interrupted and reminded them.