Prior to April 2008, the Marvel Comics character Iron Man was seen as a B-list hero at best for the mainstream audiences. Avid readers knew the character well, fans of the 90s animated Marvel shows were bound to come across him at some point, and he popped up in a few games here and there.

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All that changed when his debut feature film, Iron Man, landed and kicked off what has now become the most successful film franchise of all time; the Marvel Cinematic Universe. The film was a huge hit with fans and general audiences, and two major factors to that reception were the casting of Robert Downey Jr. in the title role and the writing that brought him to life.

10 "I Am Iron Man"

Original poster for 2008's Iron Man

As the first film started to wind down and enter its final few minutes, Tony Stark prepared for a press conference to explain the appearance of the mysterious Iron Man and to dismiss reports that he was the armored hero. He went out in front of the media and clumsily tried to brush off the questions until he made a daring move.

With a sly smirk, he put down his pre-approved notes and looked out to the crowd. With three words, the MCU was born, and viewers were elated to have their expectations subverted and see the hero publicly embrace who they are.

9 Stark's Mistakes Make Him More Relatable

Iron Man and War Machine facing off in Iron Man 2

Everyone has their flaws, and a unique aspect of the Marvel comics is that many of the big heroes also have problems to help them feel grounded. Spider-Man has the infamous "Parker luck" while Stark struggled with a very real-world issue, that of alcohol addiction.

While 2010s Iron Man 2 didn't explore that potential, it did feature a scene in which Stark buried his frustrations and fears under booze at his birthday party. With a house full of guests, the hero got himself blind-drunk and recklessly showed off while wearing his armor and putting people at risk. It wasn't his best moment, and that only helped endear him to viewers.

8 "You Guys Look Like Two Seals Fighting Over A Grape"

Tony Stark and pepper Potts

The first Iron Man featured electric chemistry between Downey Jr. and Gwyneth Paltrow, who portrayed Pepper Potts. This dynamic became an integral part of the early backbone of the MCU and brought many funny and heart-warming moments between the two.

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After defeating the deadly Ivan Vanko, Stark and Pepper flew to safety aboard a nearby rooftop as explosions rocked the area. After a typically awkward exchange, they finally kissed and shared a private moment. Or at least it should have been private if they hadn't accidentally picked the same rooftop as James Rhodes, AKA War Machine, who saw the whole thing.

7  "His Name Was Phil"

Avengers Phil Coulson

Agent Phil Coulson first arrived on the scene in the original Iron Man and his character continued to grow through the sequel. In The Avengers, fans were treated to more of the understated agent, and due to clever writing, directing, and of course acting, he made an impression on viewers that they likely didn't notice until it was too late.

Coulson was killed by Loki during his escape from the SHIELD helicarrier, but not before he could get a shot at revenge with a powerful weapon engineered from the Destroyer's appearance in 2011s Thor. Stark and the other heroes were greatly affected by this loss, and their battle against Loki took a very personal turn. Stark would remind Loki of his actions before the climax of the film, blasting him one more time in Coulson's name.

6 He Was Willing To Risk His Life To Save The Day

marvel mcu avengers iron man hawkeye black widow thor hulk captain america taking aim

As the Avengers battled Loki and his army, a nuclear warhead was sent hurtling toward New York City to try and contain the threat, regardless of the human cost that would occur. Up until that point in his life, Stark had often been labeled as selfish and arrogant, but he proved that he was far more than those things when it counted.

Stark intercepted the nuke as it approached the city and carefully guided it upward toward a portal through which Loki's alien warriors had entered. With no concern for his own safety, he flew the weapon through the gateway and into another dimension. With that selfless act, he aimed the warhead directly at a massive alien ship and destroyed it, which resulted in the alien threat being wiped out. He very nearly didn't make it back out of the portal before it closed, and even seemed to accept that death was likely approaching.

5 "I'm Just A Man In A Can"

Iron Man looking defeated

Most of the time, heroes don't suffer much negativity after they stop the bad guys and save the world. Unusually though, and quite relatable, Stark was changed after his encounters with "gods, aliens, other dimensions" and this caused him to suffer from panic attacks and insomnia.

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A large chunk of 2013's Iron Man 3 would focus on Stark's personal struggles with his own mind as well as a very real threat from Aldrich Killian. This kind of mental battle helped humanize the hero considerably and give him a conflict that many people could identify with, regardless of its extreme origins.

4 He Felt Betrayed By His Friend For Understandable Reasons

Captain America and iron Man

2016's Captain America: Civil War did the unthinkable, it split the Avengers apart into two opposing sides and threw them into an intense standoff. The outcome of the film greatly impacted the next big team-up and that was especially true when it came to the friendship between Stark and Steve Rogers, AKA Captain America.

Upon learning that Rogers' war-time friend, Bucky, was the one who killed his parents, Stark had an understandably negative reaction. As most people would, he flew into a fit of rage and tried to kill the one who took his parents from him. This was one of his darkest moments, yet it was one that few could judge him for.

3 "My Only Curse Is You"

Iron Man vs Thanos in Avengers: Infinity War

Avengers: Infinity War brought fans the battle that had been teased to come since 2012; the fight against Thanos. With the Avengers splintered following Civil War, Stark and a smaller band of heroes journeyed to the planet Titan to try and stop Thanos there and then. They were not successful.

Despite facing an immensely superior foe, the new team fought with everything they had. Stark especially would refuse to back down to the monster, claiming that if Thanos tried to throw another moon at him, "I'm gonna lose it." Stark would barely survive the encounter and would face great personal loss due to Thanos' next actions.

2 "I Love You 3000"

Tony Stark With Morgan Stark

In the 5 years following Thanos' victory in Infinity War, the world moved on after losing half of the human population. Stark returned home and after all hope of undoing the event appeared to be lost, he left the Avengers to be with Pepper.

Avengers: Endgame would see Stark living a peaceful life by the lake with his wife and adorable young daughter, Morgan. The apple clearly didn't fall far from the tree, and Morgan was able to give her father some funny and sassy backtalk when required. As he put her to bed one night, he told her that he loved her "tons," to which she replied "I love you 3000" and the entire audience welled up in unison.

1 "And I... Am... Iron Man"

Iron Man using the Infinity Gauntlet in Avengers: Endgame

Three words kicked off the MCU as the world knows it today, and those same words would circle back 11 years later in a moment that would have fans cheering, clapping, screaming, and crying in triumph and heartbreak. Avengers: Endgame saw the world's mightiest heroes assemble once more to fight the greatest fight of their lives.

For Tony Stark, that fight would also be his last. As Thanos and his army battled for the new Infinity Gauntlet, all would seem lost as the Mad Titan finally claimed his prize. Before he could execute this plan, however, Stark duped him and took the Infinity Stones for himself. Knowing that the resulting action would kill him, he stared his enemy directly in the eye and wiped him and his forces out forever.

NEXT: MCU: 5 Ways It Needs Another Iron Man-Style Central Hero (& 5 It Doesn't)