With the final episodes of Young Sheldon airing on May 16, 2024, many fans are reminiscing on the origin story's beginnings, back when the character of ultra-nerd Sheldon Cooper (Jim Parsons) debuted on The Big Bang Theory back in 2007. Back then, Sheldon Cooper was the face of the show, often expressing his all-famous catchphrase "Bazinga!" in comedic moments. Such moments often included the friendships in the show between the main cast: Sheldon, Leonard (Johnny Galecki), Penny (Kaley Cuoco), Howard (Simon Helberg), Raj (Kunal Nayyar), Amy (Mayim Bialik), and Bernadette (Melissa Rauch). This was even more so the case when certain duos were on-screen, playing off each other's humor. Although every friendship contributed to the sitcom's greatness, some friendships were simply better than others, especially when it came to working with each other's comedic timing. Here's to the best duos that appeared in The Big Bang Theory.

10 Bernadette & Amy

Best Episode: Season 8, Episode 5 ("The Focus Attenuation")

Bernadette and Amy were not always the best of friends, as Bernadette was considered a girl’s girl, while Amy did not fully understand such concepts due to her distanced and warped perception of what women enjoy doing. Their intelligence often matched each other, making them a comedic duo that often clashed, almost in a way that was similar to Leonard and Sheldon's friendship.

Sure, there were instances where Amy and Bernadette fought due to their internal — and sometimes external — conflict about being Penny's best friend, and they rarely hung out together due to this competitive lifestyle. However, despite these differences, Bernadette and Amy eventually grow closer, though maybe not as close as Amy and Penny in later seasons of The Big Bang Theory. Still, their outwardly different yet quirky personalities lead them to be a fun duo to watch on screen.

9 Sheldon & Raj

Best Episode: Season 3, Episode 4 ("The Pirate Solution")

Early on in the show, Sheldon and Raj have an underrated friendship, one where Sheldon seems to respect Raj and his intelligence more than any other person. And although Sheldon is self-absorbed, there are instances where his altruistic side comes to light for Raj’s sake. One such instance involves Raj’s potential deportation after losing his job. Sheldon, although very particular about his lifestyle, decides to use the remaining of the department’s money to hire Raj to work for him in his department. It is one of those rare instances that Sheldon offers his assistance through the kindness of his heart, though Raj rejects Sheldon’s sense of superiority in exchange for equality in terms of partnership. No one puts Sheldon in place like Raj does, making for a very comedic duo.

8 Raj & Penny

Best Episode: Season 10, Episode 19 ("The Collaboration Fluctuation")

At the beginning of The Big Bang Theory, Raj was one of the geeks known to be very shy around women. He was so shy to the point that he could not speak to them unless he drank alcohol, allowing him to be free of his fears. This was especially true when Penny came into their friend group, where Raj would use Howard to relay information.

However, in later seasons, Raj and Penny become undeniably close. This is especially true when Raj moves in with Penny and Leonard. Raj joined in on Penny’s daily routine, matched outfits with her, and listened to her work drama. Additionally, Raj’s ability to talk to women while drinking alcohol came to light when Penny made him a few drinks to practice her bartending skills. Although it came later on, Raj and Penny’s friendship was one to cherish, and the two completed each other in unexpected ways.

7 Penny & Bernadette

Best Episode: Season 6, Episode 13 ("The Bakersfield Expedition")

Bernadette was first introduced in Season 3 of The Big Bang Theory, serving as Howard’s blind date and first appearing as Penny’s waitress colleague. Before Amy became super close to Penny, Penny and Bernadette were close friends — practically, even best friends, until Amy came into the picture. Sometimes, Bernadette found herself jealous enough to the point that she felt the need to compete for Penny's attention, but that alone proved their closeness and her fear of losing Penny.

Penny and Bernadette’s friendship is as clear as day, as both are very similar in behaviors and attitudes. This dynamic allowed the two to understand each other and their interests on a deeper level. While they have clear and distinct differences, Penny and Bernadette share a lot of similar hobbies and interests. They are the perfect image of a girl’s best friend and why they are loved so much as a duo.

6 Sheldon & Amy

Best Episode: Season 10, Episode 24 ("The Long Distance Dissonance")

Sheldon and Amy first dated on a transactional basis to please their mothers. Neither of them knew what love was, nor were they interested in it. The two were intelligent people who distanced themselves emotionally from others, not as a means of distrust, but rather because they did not share the same emotional capacity as others. Sheldon’s stoic and often misconstrued selfish attitude proved that much. Meanwhile, Amy did not fully understand what it was like to be a best friend, which Bernadette and Penny expressed in their relationship.

Unlike other characters in the show who were considered “normal,” Amy and Sheldon were different from the rest; they understood each other much more deeply than anyone else could. They were almost the same person, yet Amy was the first one to really want to indulge in the same romantic gestures expressed in her friends’ relationships. Most importantly, although Sheldon felt a little different in that regard, he eventually opened up these romantic gestures, flying himself out to be with Amy after being kissed by another woman. It was in this revelation that Sheldon found himself wanting to marry Amy, thus creating one of the most romantic duos in The Big Bang Theory.

5 Sheldon & Penny

Best Episode: Season 1, Episode 11 ("The Pancake Batter Anomaly")

Sheldon and Penny were not on great terms at first on The Big Bang Theory. Penny didn’t understand Sheldon’s particular ways, as seen when she sat on his side of the couch and forced him to sit elsewhere (though he was very unhappy about it). Likewise, Sheldon did not understand her boundaries and broke her trust when he broke into her apartment to clean it up and organize it.

Sheldon and Penny have definitely been through thick and thin with one another, stepping into each other’s widely distinct and different worlds in order to understand each other and overcome their differences. One special moment they shared was when Penny gave Sheldon a napkin that was used by Leonard Nimoy for Christmas. This act alone showed that Penny understood Sheldon’s geek culture, going as far as to do something weird to make him happy. Likewise, Sheldon gave her plenty of gifts in return, but one of the most shocking moments was when he gave Penny a hug, a gesture that made Penny incredibly happy.

4 Howard & Raj

Best Episode: Season 12, Episode 22 ("The Maternal Conclusion")

Howard and Raj were good friends throughout the entirety of The Big Bang Theory. They understood each other on a deep level, never afraid to get a little weird with one another at certain times. Raj and Howard needed each other; Raj had a hard time speaking to women, and oftentimes, Howard would be his voice.

One of the more key components of their friendship, though, appears when Raj and Howard begin to have a falling out. Such instances include Raj feeling resentful toward Howard for bailing on him to seek out women and vice versa when Howard feels betrayed as Raj develops feelings for his wife, Bernadette. However, despite these falling-outs, Howard and Raj prove to be valiant friends who are able to overcome hardships and continue their so-called “bromance,” showing viewers that friendships can overcome difficult scenarios so long as there is mutual understanding and communication.

3 Penny & Amy

Best Episode: Season 11, Episode 12 ("The Matrimonial Metric")

Penny and Amy are unlikely best friends that came to be in later seasons. Around Season 6, Penny and Amy see much more of each other because of their boyfriends, with Penny dating Leonard and Sheldon dating Amy. At first, they were on awkward terms due to Amy’s possessive and obsessive nature and Penny not quite yet considering Amy a close enough friend.

However, once Penny and Amy grow close, it’s hard not to see them as an iconic best-friend duo. Coincidentally, once Amy and Penny start hanging out with one another, they realize they have more in common than they think, understanding each other on a deeper level than they initially expected, which is especially clear when they beat best friend duo Leonard and Sheldon at Pictionary during game night.

2 Leonard & Penny

Best Episode: Season 12, Episode 12 ("The Stockholm Syndrome")

The pairing of Leonard and Penny is an obvious fan-favorite, marking them as one of the most iconic couples in sitcom media and on The Big Bang Theory. Though socially awkward at first, Leonard tried to constantly flirt with Penny and help her out whenever she needed, though she did not initially understand the nerd culture that he lived in.

Although they had their ups and downs through breakups and insecurities, Penny and Leonard proved that even though they were distinctly different people from very different — and sometimes complicated — worlds, they could make it by showing interest in each other's hobbies and lifestyles. Furthermore, while the two were at a completely different pace in their relationship, they made it work.

1 Leonard & Sheldon

Best Episode: Season 11, Episode 24 ("The Bow Tie Asymmetry")

Leonard and Sheldon are the best duo throughout the entirety of The Big Bang Theory. From the beginning, with Sheldon’s socially awkward mentality and Leonard’s insecurities, the two demonstrate a strong friendship, making up for the other in the areas that they lack. While Leonard struggled with being honest in communication, Sheldon had no problem expressing his and Leonard’s thoughts. Meanwhile, Leonard was able to communicate things and concepts that were abnormal to Sheldon.

More importantly, Leonard and Sheldon were the best friends that everyone wanted. While they had their ups and downs, they always made up in the end. Sure, Leonard often criticized Sheldon’s ability to socialize through a means of sarcasm, but that made their friendship all the more humorous, especially when Sheldon shot back through a methodological way of speaking, though it was often unintentionally insensitive. Still, this best friendship was ultimately the duo that started the entire series.