Over the course of the Marvel Cinematic Universe, arguably no character has changed more than Tony Stark. In his initial movies he was, as described by himself in The Avengers, a "genius, billionaire, playboy, philanthropist."

RELATED: MCU: 5 Reasons Why Phase 1 Was The Best Era (& 5 Why It Was Not)

Tony always remained a wealthy and resourceful genius, but he transcended those labels as he grew into a more complex and better version of himself. He stepped up and bravely tackled many of the fears and insecurities that held him back. Sometimes he saved the day, sometimes he failed miserably, and most importantly, he felt like a delightfully sarcastic human trying to be better.

These are the 10 biggest ways Tony Stark changed throughout the MCU.

Changed The Direction Of Stark Industries

Stark Industries New York HQ

Stark Industries profited off creating and selling some of the best weaponry in the world. When Tony was captured by the terrorist organization known as the Ten Rings, he saw them ruthlessly use weapons that his company created. After Tony escaped captivity, he changed the direction of the company by declaring that they would no longer produce any weaponry.

As Tony focused on his life as Iron Man, he wisely stepped down and appointed Pepper Potts as CEO of the company. Stark Industries flourished under her leadership. Pepper and Tony also used the company to fund the Stark Relief Foundation, which provided aid to those affected by the carnage left in the wake of Avengers-related battles.

Learned To Be A Team Player

The Avengers 2012 line-up

Tony is the kind of guy who likes to handle everything himself. This made it a challenge at first for him to work with the other Avengers.

In The Avengers and throughout the rest of the MCU, he learned more and more how to become a team player, work well with others, and lead by example. He even formed close relationships with some of the other Avengers like Steve Rogers and Bruce Banner and relied on them in some of his darkest and most desperate moments.

Committed To Pepper

Through all his ups and downs, Pepper Potts always stayed by Tony's side. Tony finally realized this, stopped messing around, and fully committed himself to Pepper. He became a faithful husband and together they created a family and a fruitful life together.

RELATED: Tony Stark's 5 Funniest (& 5 Most Heartbreaking) Quotes In The MCU

This might not sound like a big deal, but it is for a former womanizer who once slept with a reporter who asked him if he ever lost an hour of sleep his whole life and he replied, "I'd be prepared to lose a few with you."

Struggled With PTSD

Robert Downey Jr in Iron Man 3

Tony faced imminent death when he guided a nuclear missile to close the wormhole in The Avengers. He saved the day and miraculously survived, but he didn't walk away unscathed. Iron Man 3 saw him struggling with post-traumatic stress disorder. Tony had already defeated his fair share of super-villains, but now he needed to learn how to handle the internal conflict of dealing with his past traumas.

This is a much more nuanced and complicated battle than what Tony had experienced before, one that continued to affect him throughout the rest of the MCU. The Battle of New York continued to weigh heavily on his mind and influence his decisions, even all the way into Avengers: Infinity War and Avengers: Endgame.

Wanted To Be Put In Check

Earlier in the MCU, Tony clashed with government authorities. He wanted to maintain full autonomy of his Iron Man tech and be able to make the right decisions without government intervention.

His beliefs changed drastically after many innocents lost their lives during the Battle of Sokovia. Tony felt responsible as it was his idea to create Ultron in the first place. This made Tony believe that he and the rest of the Avengers needed to be put in check via the Sokovia Accords. Once the most reckless members of the Avengers, he was now trying to be one of the most responsible by holding himself and his friends accountable for the consequences of their actions.

Became A Father Figure And Mentor

When Tony needed another superhero on his side in Captain America: Civil War, he reached out to the young Peter Parker. Little did Tony know that this would lead to one of the most important relationships in his life, one where he would become a father figure and mentor.

RELATED: MCU: 10 Best Unused Ideas From Phase 3

Tony taught Peter what it really means to be a superhero. He helped shape Peter into a more responsible and wiser young man. Peter also influenced Tony in positive ways, helping Tony realize what it means to be a father. Their bond was so strong that it became a driving force for Tony to risk everything and try to bring Peter and countless others back in Avengers: Endgame.

Grew To Understand His Father

Tony Stark Howard Adopted Father

Tony had a difficult and sometimes contentious relationship with his father Howard Stark. These issues were left unresolved after the sudden and tragic deaths of Tony's parents.

In Iron Man 2, Tony saw a message that Howard left for him, which allowed him to begin better understanding and appreciating his father. The message made clear that Howard fully believed in Tony and the better future he would help create, along with the touching line that "What is and always will be my greatest creation . . . is you." In one of the alternate realities in Avengers: Endgame, Tony was even able to have one final conversation with his father and receive the closure he needed.

Reconciled With His Past Mistakes

Steve Rogers and Tony Stark talk in Endgame

Despite his massive ego, Tony learned how to face his mistakes and be better because of them. After feeling responsible for the destruction caused by Ultron, he pushed for the Sokovia Accords. Even though he had good intentions, this split the Avengers apart.

In Avengers: Endgame, Tony owned up to the mistakes he'd made and reconciled with Steve Rogers. By letting go of the bitter feelings that created their old conflict, he and Steve were able to work together again, reunify the Avengers, and lead them on a path that would change things for the better.

Became A Father

Tony Stark Morgan

Tony and Pepper had a child of their own who they named Morgan. Tony proved to be a wonderful father to her. He was loving, goofy, and made her feel safe. They played together, ate cheeseburgers together, and they loved each other 3000.

He loved her so much that he was almost willing to risk the fate of the entire universe in order to protect her. The possibility of losing her and Pepper was the main reason he was initially resistant to finding a solution to bringing everyone back from Thanos's Snap.

Sacrificed Himself To Save The Universe

Iron Man snaps his fingers wearing his version of the Infinity Gauntlet in Avengers: Endgame

Tony used to only care about himself, yet he developed into someone willing to sacrifice himself in order to save his family and the entire universe. At the climax of Avengers: Endgame, Tony swiped the Infinity Stones away from Thanos and snapped his fingers.

This action defeated Thanos and saved everyone in the universe from Thanos's ruthless plan. Morgan, Pepper, Peter Parker, and everyone in the universe now had a chance to live and fulfill their dreams because of the incredible sacrifice that Tony made.

NEXT: 10 Characters Who Could Be The MCU's Next Big Death