On The Big Bang Theory, the core friend group went through a lot, both professionally and personally. But some characters grew more than others.

The main characters ofThe Big Bang Theory have been through a lot over 12 seasons. In the first season, Sheldon, Leonard, Howard, and Raj were self-admitted nerdsand did nothing but work and dream about dating a girl one day. Fast forward to the final season, most of the characters have long-term relationships and have made valuable contributions to science and society.

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They have been through a lot together as a group and transformed into differentpeople by the series finale. However,the gang did not develop and growequally. Some character arcs were downright lackluster compared to others.

It's sadto say, Leonard didn't grow much over 12 seasons. Sure, he was able to become a loyal and dedicated husband to the woman of his dreams but he let some aspects of his life slide. Unlike the rest of his friends, Leonard didn't make the same kinds of contributions to science. Sure, he was a part of incredible projects but when comparing friends, Leonard was the least successful.

In his personallife, Leonard whined a lot and became complacent. He was also jealous of Penny's success and didn't know how to handle her not needing him like she used to. Leonard is a standup guy and a devoted friend but his character arc was the least compelling among his friends.

When viewers met Bernadette, she was a shy woman with a high-pitched voice who laughed at Howard's jokes because it made him happy. But as time went on, it was obvious that she was insanely bright and more put-together than Howard was. She went on to get her Ph.D. before landing a very profitable job in microbiology and later became a wife and a working mother of two.

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While that's all very impressive, Bernadette's personality faded as her career took off. She became more judgmental and snarky in the group. She bossed Howard around, treated him like a kid when it came to finances, and even got into arguments with the ladies. It was wonderful to see her successful but her personality took a dark turn.

Stuart Bloom didn't start out as a main character but he might as well have been one by the 12th season. He was the owner of the comic book store that the gang went to weekly. Stuart was always there and became an important part of their inner circle.

He was poor, desperate, and hungry for most of the series but once he got his comic book store up and running after the fire, things turned around for him. His shop became popular, he started dating Denise, he was hanging out with the group more often, and he seemed to finally be financially stable. It was nice to see Stuart have a happy ending for a change.

In season 1, Raj was unable to speak to women because of his selective mutism. This made it hard for him to socialize with his friends, especially when the gang befriended Penny.But by the final season, Raj no longer needed alcohol to speak to women and was a confident man. He made extraordinary finds in science, like the space prob, comet, and possible alien life. He even started working part-time at theplanetarium to further his love of science.

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In his private life, Raj made the decision to stop relying on his parents and started from the ground up to solidify himself as a self-made man. He even started being more honest with the different women that he dated. And while fans wanted him to end up with Anu, he showed tremendous character growth by calling off the wedding. Season1 Raj would have gone through with it.

Fans didn't meet Amyuntil the third season, but she's one of the most transformative characters in the show. Neuroscientist Amy had a robotic voice and said exactly what she was thinking, even if it offended others; she was basically the female Sheldon.

But by the series finale, Amy was no longer that cold and distantwoman.She was a Nobel Prize winner, dear friend, and a loving wife. She learned to open up and trust others and have the life her younger self always dreamt of. It was fulfilling for fans to see Amy's character arc so full and fleshed out.

Despite Penny's apparent dependency on a glass of wine and her snarky responses to Leonard, fans can't ignoreher success story. She came to Las Angeles as a 21-year-old girl with hopes of being an actress. She waited tables at the Cheesecake Factory and barely got by financially. She dated jerks who took advantage of her and she didn't have any true friends.

By the finale, Penny was whole. She was married to her best friend, was an integral part of her friend group, was taking classes at the community college, and started a successful job in pharmaceutical sales. Penny was doing so well at work that Bernadette promoted her! Penny was no longer the poor wishful thinker that she was in season 1. She was now a driven woman with a good head on her shoulders.

Howard Wolowitz's character arc is nothing short of a miracle.While he was one of the funniestmembers of the group, Howard also started off as the creepiest. His behavior towards women was concerning and he didn't treat many people with respect (including his buddy Sheldon). That all changed when he met Bernadette.

Howard went from a wannabe womanizer to a loving husband and father of two. At work, Howard'scareeras an engineer got him to outer space and a job with the United States Military. As outgoing and goofy as Howard is, his contributions to science are some of the most impressive in the group. It was eye-opening to see someone make a complete 180 transformation.

It shouldn't be too surprising that Sheldon's character arc was the best out of his friends.He is a completely different person than the man viewers met in season 1. With the help of his wife Amy, Sheldon was able to understand sarcasm, become a good listener, come to be empathetic, and even became a better scientist. He warmed up to girls and the idea of being selfless. And with Amy's help,he became a Nobel Prize winner.

Sheldon dedicated his life to science but grew as a man, partner, and friend at the same time. Sure, Sheldon still had annoying tendencies but he's a much more understanding man by season 12.

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