Although The Big Bang Theory is an ensemble cast, the friendship between Leonard and Sheldon was one of the strongest in the series.
Leonard Hofstadter and Sheldon Cooper are just two people of the loving friend group on The Big Bang Theory. Although the series is an ensemble cast, Sheldon and Leonard are two of the more important characters because of their friendship and living status. As best friends and roommates who don't always get along, their moments together are some of the fans' favorite.
Through all of the betrayals they've had or the lies they've shared, Leonard and Sheldon are best friends and were the best pairing on TBBT.
In the last episode of TBBT, Sheldon and Amy finally accept their long-awaited Nobel Prize medal. The moment was a big one for the couple, but primarily Sheldon. Sheldon has driven many of his friends—especially Leonard—crazy with his hopes for success and he finally achieved it.
In his acceptance speech, Sheldon's best quotes towards his friends were shared. It was one of the best moments between Sheldon and Leonard that showed how much their friendship had grown.
In 'The Parking Spot Escalation,' Sheldon is feuding with most of his friends when Howard is given his parking space at Caltech. It didn't make sense that Sheldon would need the parking lot without a car, but he justified that it was his spot.
In the episode, he asked Leonard why he never took his side and Leonard honestly shared that he never understood Sheldon's side. The moment was a humorous one that showed that Leonard and Sheldon were honest with one another in times of defeat; a sign of a great friendship. Though Sheldon didn't always handle things well, Leonard's honesty came out in the end.
Leonard and Sheldon were at a crossroads in 'The Space Probe Disintegration.' While out shopping with Penny and Leonard, they started talking about their future as roommates. Leonard and Sheldon were best friends but there was going to be a time when the roommate agreement no longer mattered and one of them would move out.
The duo began bickering with each other before realizing it came from the fear of no longer living with each other. Leonard said this sweet quote to Sheldon, which made him feel better. This moment was one of the pair's best moments as friends.
Sheldon and Penny had one of the best friendships in TBBT, but it wasn't better than Sheldon and Leonard's.
When Leonard and Penny gave their relationship yet another try, Sheldon caught wind that Penny was unsure of her feelings and didn't know if dating Leonard was the right decision. This hurt Sheldon knowing that his best friend was going to be potentially heartbroken again. He had a midnight conversation with Penny and adorably begged her not to hurt his friend. It was an emotional quote.
Penny and Leonard didn't have the best relationship with Leonard's mother, so to do right by her, the couple had a second wedding where they invited friends and family. With a brief wedding to plan, Sheldon said a touching speech in front of their loved ones.
In the speech, Sheldon admitted the two were more than best friends — they were family. At this moment, all of the annoying things that bothered Leonard about Sheldon disappeared. It was yet another reason why their friendship was one of the best in the series.
Just like when Leonard and Penny got married, Sheldon and Leonard shared a sweet moment at Sheldon's wedding.
The two men were getting ready for the big day and Leonard told Sheldon how happy he was for him and that he was now (finally) Amy's problem. The joke broke up the emotional parts of the scene, and it got better when Sheldon admitted that despite having Amy he'd always be Leonard's problem. It was a sweet bromance moment between the two.
When Professor Proton (Arthur Jeffries) came into Sheldon and Leonard's lives, the two friends were starstruck. Arthur was a beloved TV scientist and they had great respect for him. Sheldon became jealous when Leonard started working with Arthur, but in retrospect, Arthur couldn't stand Sheldon.
While in the lab, Arthur asked Leonard why he put up with Sheldon if he was so bothersome all the time. Leonard replied sweetly that although Sheldon was broken, they both needed each other. Sheldon matured through the series and became easier to be around, which helped their friendship.
When Arthur Jeffries passed away, Leonard was afraid of how Leonard was going to take it. Sheldon didn't handle loss well and Arthur became a dear part of his life. Sheldon acted cold to Leonard at first but after dreaming of Arthur and being reminded to hold his loved ones close, Sheldon did just that.
In a sweet moment of friendship, Leonard checked on Sheldon after his nap and Sheldon hugged him dearly. As usual, the tender moment was broken up by sarcastic jokes but it was a scene that made their friendship outshine others.
At the end of season 7, Sheldon was going on a train ride around America to clean his head after a lot of heavy changes plagued his life. Even though this meant that Leonard and Penny would finally have alone time, it was bittersweet saying goodbye to Sheldon.
Leonard longingly looked at his best friend and told him he'd miss him, and hilariously, Sheldon pulled a classic Sheldon move and said, "Of course you are." Though Sheldon didn't say it, it was obvious the two would miss each other since they were best friends.
When the Physics Bowl came to Caltech, it was obvious that Sheldon and Leonard would be on a team with Raj and Howard. However, when training for the competition, the group was angered that Sheldon was hogging all of the questions and not being a team player.
Even though they were best friends, Leonard knew the best thing for their friendship was to kick him off the team. To ease the pain, Leonard gifted him a Batman cookie jar while firing him. This scene showed that they could still be brutally honest with each other without ending the friendship, making them one of the strongest in the series.
