When "Iron Man" first premiered back in 2008, fans couldn't begin to dream of just what Kevin Feige and Marvel had planned. The film, which was meant to be a comeback for Robert Downey Jr., was considered to be a risk for Marvel, who until that point, had never attempted to adapt any of their own comics into film. With so much riding on the project and the uncertainty of it being a commercial success, the idea of the Avengers hitting the big screen in the future seemed like nothing more than a fever dream.

RELATED: Black Heroes Matter: 17 Black Defenders Of The MCU

Fast forward to 2017, and the Marvel Cinematic Universe is now one of the biggest franchises in the world, spanning 12 films and nearly just as many television shows. With that said, here is a list of the 15 biggest moments from the Marvel Cinematic Universe so far -- some of which actually take place off the screen!

15 BLACK PANTHER

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Over the course of eight years, Marvel Studios has managed to do something most studios could only dream of: build a massively successful cinematic universe. From 2008's "Iron Man" to "Guardians of the Galaxy," the studio has proven that it is willing to take risks occasionally, with those risks ultimately working in its favor. However, in recent years, fans have been very vocal in their desire to see more than another film headed by a white male lead. One character in particular fans have been eager to see brought to life on the big screen is that of T'Challa, aka the Black Panther.

Many will note that once upon a time, long before the Marvel Cinematic Universe was a reality, Wesley Snipes was trying to make a Black Panther film with director John Singleton. That, of course, never happened and Snipes went on to head "Blade." But that was the closest fans had gotten to a Black Panther film until Marvel announced in 2014 that, not only would actor Chadwick Boseman head his own solo film as the character, but he'd also first appear in "Captain America: Civil War." During the short amount of time "Civil War" focused on Boseman's story, the actor proved that his casting as the hero was easily one of Marvel's best casting decisions to date.

14 SONY & MARVEL TEAM-UP

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After years of wishing and constant rumors of the seemingly impossible happening, it finally happened. Marvel and Sony announced that they'd work together to find a way to bring Spider-Man into the Marvel Cinematic Universe. After five individual solo Spidey films, Spidey was finally able to work alongside his fellow Avengers. It was a new start for Sony, which was struggling following the poor box office performance of "The Amazing Spider-Man 2," as well as the beginning of new possibilities for Marvel Studios.

In the two years since the announcement, Tom Holland made his debut as the Marvel Cinematic Universe's Spider-Man in last year's "Captain America: Civil War," and is set to star alongside the man that started it all, Robert Downey Jr., in this summer's "Spider-Man: Homecoming." Marvel Studios head Kevin Feige also made it official by confirming the web-slinger would be joining both the Avengers and the Guardians in the upcoming "Avengers: Infinity War."

13 THE DEFENDERS

Following the success of "The Avengers," Marvel decided to try and recreate that crossover success using its street level characters and taking them to the streaming service in a major deal. It was a huge shock for fans, as the deal came shortly after the rights for Daredevil -- who was included in the line-up -- had finally reverted back to Marvel.

Although many originally hoped to see the man without fear lead his own film within the MCU, Marvel opted to instead give the character 13 hours on the small screen. It was a new corner for the MCU, proving to be much darker and far more mature than what we had come to expect from the Marvel brand. The shows, which brought us Daredevil, Jessica Jones, Luke Cage and Iron Fist, aren't afraid of killing off major characters -- as evidenced by the death of Ben Ulrich in "Daredevil" season one -- and tackling controversial, yet important, topics such as race and sexual assault. "The Defenders" proves that Marvel is willing to continue pushing boundaries and the Marvel Cinematic Universe is better for it.

12 AGENTS OF S.H.I.E.L.D.

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"Agents of S.H.I.E.L.D.," although a poor ratings series for ABC, has proven to be such a vital part of the Marvel Cinematic Universe since its debut back in 2013. Developed to act as a companion to the films, "S.H.I.E.L.D." saw the resurrection of fan-favorite character Phil Coulson, played by actor Clark Gregg, a character that was originally killed off by S.H.I.E.L.D.'s Executive Producer and "The Avengers" director Joss Whedon in 2012. Alongside Coulson, a new group of S.H.I.E.L.D. agents was brought in, none of which -- at the time -- had existed within the comics.

Fast forward to 2017, and not only have two of those characters turned out to be comic characters -- with Chloe Bennet's Skye turning out to be Daisy "Quake" Johnson and Brett Dalton's Ward becoming the Inhuman Hive -- but the series has since been integrated into Marvel Comics. Even more surprisingly, in recent seasons, the show has made it a point to not just connect to the films but to also introduce established comic characters, proving it's more than capable of standing on its own apart from the films.

11 AVENGERS ASSEMBLE

"The Avengers" holds a special place for many Marvel fans. Not only was it the first time we got to see Mark Ruffalo's portrayal of the Hulk, it was also the first time all of the Avengers came together on screen. The film, written and directed by Joss Whedon, saw the heroes team-up to take down Tom Hiddleston's Loki, who at the end of the film, was revealed to be working for none other than Thanos, the mad titan. That was a huge reveal that set up the rest of the Marvel Cinematic Universe, one that we'll finally get to see come to fruition when the third Avengers film debuts in 2019.

It has been nearly five years since the original Avengers team came together on screen, and although Marvel has continually upped the bar on its films, it's still often viewed as the quality bar for all superhero flicks. That is a huge accomplishment for a studio that, at one point in time, saw the team-up film as merely a dream.

10 AVENGERS DISASSEMBLED

As big of a deal as it was to see the Avengers come together in the first Avengers film, seeing the team go against each other to bring the divisive "Civil War" storyline to life was an even bigger moment in the Marvel Cinematic Universe. These were characters we'd come to love seeing as a united front, and now, here they were playing into the villain's plan, tearing the team apart from the inside. Although none of our heroes died, there were plenty of consequences to be had for their actions.

Rhodey was badly injured, Bucky lost his arm - again, and the team as a whole was fractured. The end of the film left our heroes broken. Thankfully, with multiple films still to come before 2019's "Avengers: Infinity War," there's still plenty of time to bring our heroes back together. However, one thing is for sure, the team dynamic will forever be changed.

9 THE DEATH OF QUICKSILVER

In a universe that hasn’t experienced much death -- permanent death, that is -- Whedon’s decision to kill off a new Avenger was like a punch to the gut. Before "Avengers: Age of Ultron" premiered, rumors began to circulate that Hawkeye, a character who hadn't received much in the way of a storyline up until that point, would likely be the Avenger to die at the hands of Ultron. That, of course, wasn't the case. In fact, not only did the archer finally get a proper story this time around, his life had been spared by a fellow Avenger -- newbie Quicksilver, played by "Kick-Ass" actor Aaron Taylor-Johnson.

It was a massive shock as fans waited, assuming the team would figure out a way to bring him back, but that never happened. The Marvel Cinematic Universe had actually killed off one of the Avengers; it wasn't just another fake out. There have been three Marvel Studios films since "Avengers: Age of Ultron," and thus far, the studio hasn't reversed the speedster's death. However, now that "Avengers: Infinity War" is on the horizon, anything is possible.

8 JOSS WHEDON LEAVES

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When "The Avengers" was first announced and Joss Whedon was confirmed to both write and direct it, fans knew they were in for a treat. Not only was Whedon behind some of the biggest geek hits -- including "Buffy the Vampire Slayer" and "Firefly" -- but he shared a passion for these characters and the world Marvel was trying to craft as a former comics writer, himself. So it wasn't entirely surprising that the film proved to be a massive critical and box office success.

Unfortunately, the second Avengers film, "Avengers: Age of Ultron," wasn't as big a success on either front, and Whedon seemed to lose the passion he'd displayed with "The Avengers." After devoting years of his life to these huge films, the director just wanted to take some time to himself to work on projects near and dear to him; projects that wouldn't allow for a bit more creative control. But for fans, the loss of Whedon seemed to be a major loss for Marvel Studios, leaving them to worry about the future of the Avengers franchise. Thankfully since then, "Captain America" helmsmen Joe & Anthony Russo have stepped in to take over for Whedon, and they're currently hard at work on the next installment, "Avengers: Infinity War."

7 INFINITY WAR

After years of teasing it, Marvel finally announced "Avengers: Infinity War" much to the delight of fans back in 2014, and they did so with a video highlighting the Infinity Stones within the Marvel Cinematic Universe up to that point. Of course, while that video ended with Thanos sporting his Infinity Gauntlet, gleaming with the aforementioned Infinity Stones, the Mad Titan has yet to actually get a hold of any -- a running joke among fans.

Thankfully for Thanos, there are a few more films to come before "Infinity War," including "Spider-Man: Homecoming," "Black Panther," and the otherworldly "Thor: Ragnarok." The third installment of the Avengers franchise, which will see Thanos serve as the main character this time around, is set to serve as the culmination of everything that came before it. With that in mind, and Marvel set to launch a new line-up of heroes with Doctor Strange, Black Panther, Spider-Man and Captain Marvel, it's hard to believe all of our heroes will come out unscathed.

6 TOM HOLLAND: SPIDER-MAN

Following the news that Spider-Man would finally be joining the Marvel Cinematic Universe, fans were eager to see which actor Marvel and Sony would cast in the role. After all, with this new deal, they'd be starting from scratch, essentially scrapping Sony's the Amazing Spider-Man franchise, and with it, it's star Andrew Garfield. For a while there, it appeared that nearly every young up & coming actor was in contention for the role, but one name continued to be tossed around in the rumored lists by the trades: British actor Tom Holland.

Holland, who, up until that point, hadn't really had a breakout role, seemed to be attached to every shortlist that would hit, so when it was finally confirmed that he'd gotten the role, it wasn't entirely surprising (especially when both Chris Evans and Robert Downey Jr. gushed about Holland's auditions throughout the casting process). Now, having seen Holland in the role in "Civil War," albeit briefly, it's hard to deny the actor has managed to truly capture Peter Parker, much like how Downey Jr. captured Tony Stark. And with a six-picture contract in place, Holland is set to play a large role going forward in the Marvel Cinematic Universe.

5 INHUMANS TO ABC

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After announcing a film for the Royal Family originally set for 2019, Marvel moved the Inhumans from the film slate to the television side, and did so with an unprecedented deal with IMAX. The move came after nearly a year of rumors suggesting the studio had secretively killed the project. With Inhumans debuting in the Marvel Cinematic Universe courtesy of "Agents of S.H.I.E.L.D.," fans were curious how the film would go about tackling the Royal Family and the subject of Inhumans. After all, although the Marvel television shows do take place within the cinematic universe, there has always been a bit of a divide between the two. Now, it appears rather than trying to tie-in the events of "Agents of S.H.I.E.L.D." into a possible film, Marvel has decided to alter its original plan to react to the television side -- a huge first.

Although Kevin Feige continues to state an Inhumans film is still possible, we'll get our first look at Black Bolt and the Royal Family this September, when the first two episodes will debut in IMAX theaters for a limited two-week run. Following the limited IMAX release, the remainder of the show's first season will play out weekly on ABC. Unfortunately, although it's coming after the events of "Agents of S.H.I.E.L.D., " this new series will not serve as a spin-off, meaning it's highly unlikely we'll see Daisy "Quake" Johnson -- or the rest of SHIELD -- make an appearance.

4 AN INHUMAN INTRODUCTION

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"Agents of S.H.I.E.L.D." typically reacts to the films, which is why it was surprising to see the series overstep the MCU by actually introducing Inhumans to the universe a good three years before the film was originally planned to debut. Granted, Marvel didn't use the Royal Family to do so, but the series did offer us our first look at both terrigenesis and Terrigen Crystals. The series, once focused on S.H.I.E.L.D. agents responding to the events of the films, turned its focus to Inhumans, bringing in both characters from the comics and creating new characters specifically for the series.

This, of course, was because, while the series was given the go-ahead to introduce Inhumans on the show, it couldn't necessarily use the Royal Family due to the previously announced film. Since then, though, major changes have taken place regarding that project, and the Royal Family is set to star in their own ABC series later this year. Whether that means we'll get to see a crossover between the two is yet to be seen, but one thing is for certain, "Agents of S.H.I.E.L.D." more than likely played a role in the decision to bring the Royal Family to the small screen -- and that's huge.

3 JOSH BROLIN: THANOS

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Casting Thanos was always going to be tricky. Marvel had to get the right actor, with the right voice and the right presence to truly carry the villainous role. Thankfully, the studio managed to do just that when it cast actor Josh Brolin in the role. The actor made his debut as the Mad Titan in 2014's "Guardians of the Galaxy," where in just a few minutes of screen-time, he managed to deliver a haunting performance, one that promised what was yet to come.

Since his casting in the role, Brolin has been very vocal regarding his excitement and why he signed on for the character. For Brolin, the idea of getting to be the big bad, and have it be Thanos vs everyone was just too exciting to pass up. And while Thanos has only briefly appeared on screen thus far, the character is set to be the main character in "Avengers: Infinity War," giving Brolin the chance to showcase just what he's capable of as the Mad Titan -- hopefully not just from his throne this time around either.

2 THE FALL OF MARVEL'S CREATIVE COMMITTEE

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One of the biggest moments within the Marvel Cinematic Universe was actually one that took place off-screen. In 2015, it was announced that the Marvel Creative Committee, a team of Marvel Comics writers assembled by Ike Perlmutter to oversee the Marvel Studios films and offer up suggestions and changes, would be disbanded. With Perlmutter no longer running the film side, Kevin Feige, who now reports directly to Disney Studios chief Alan Horn, got rid of the Marvel Creative Committee on the studio's films. It was a move that allowed for more control over the future of the universe, while also allowing directors more ability to retain their vision over their projects, something that had been a problem in the past for the studio.

With "Doctor Strange" having previously been said to be the last film the committee had any say over, given just how long it was in the works, it's expected we'll see the effects of the changes behind the scenes with this year's releases. This includes the highly anticipated "Guardians of the Galaxy: Vol.2 " which has just scored a super rare 100% at a test screening. Since the disbanding of the committee, Marvel Studios has brought in a more diverse line-up of talent to both write and direct its forthcoming features, including director Taika Waititi ("Hunt for the Wilderpeople") who'll bring "Thor: Ragnarok" to life on the big screen later this year.

1 GUARDIANS OF THE GALAXY (OR, GROOT)

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Although still a relatively new franchise for the mega studio, it's hard to remember a time before the Guardians joined the Marvel Cinematic Universe. A group made up of misfits, including a walking, talking tree and a gun-wielding raccoon, seemed like a weird mix on paper; and yet, director James Gunn somehow magically made it all work in 2014's "Guardians of the Galaxy." The movie had many things working against it, including the fact that the general public didn't know a thing about these characters that were -- putting it nicely -- considered to be "D-List" prior to the film. Not helping was the fact that the movie was just generally more "out-there" than the other Marvel films before it.

As box office numbers for the first weekend came in, beating estimates by nearly $35 million, it became clear that Marvel had managed to deliver another quality product, all while getting people to care about a tree capable of an extremely limited vocabulary. A film that was once viewed as a risk for the studio ended up proving that, not only was Marvel still on top, but it was also willing to take risks –- risks that paid off surprisingly well, as the Guardians quickly became another hit franchise for the studio.

What do you think are the biggest moments in the Marvel Cinematic Universe? Let us know in the Comments!