The longer the MCU goes on, the more divisive the movies seem to be. While they're mostly given rave reviews and the critics are all on board, the general public is getting more hesitant. There have been complaints of Marvel putting together a formula that's starting to get old very quickly.
Another big complaint that's said a lot is that the MCU, while it does justice to a lot of characters, butchers a lot of other aspects of the source material. There's a great history that spans decades in the Marvel Universe, with many iconic events taking place in that period. Despite how important some of these things are, they haven't been faithfully represented in the movies.
Understand that simply because a comic book movie doesn't adapt the source material to a "t" doesn't make it bad. Sometimes, there are certain restrictions that hold a movie back that don't exist with a comic book. That said, there are many times where something like this has occurred in the MCU, which led to a big change, for better or worse.
While they don't define the quality of the films, the MCU is known for changing a lot of the source material to fit the big screen. Here are 15 times the Marvel Cinematic Universe butchered the comics. Marvel fanboys, plug your ears for this one.
15 Arnim Zola
Arnim Zola is one of the stranger characters of the Marvel Universe. Being an old scientist, his consciousness was preserved in a machine that he then used to create a mechanical body and work with HYDRA in the modern day. Because of this, he had extra strength and power so that he could go toe to toe with the Avengers.
In the MCU, Zola took a much more subtle approach. After being a part of Captain America: The First Avenger, his body decayed but his consciousness was preserved in a supercomputer in Winter Soldier. However, he only existed as a means of dumping information and telling Cap that HYDRA had been secretly infiltrating SHIELD the entire time. He was also eliminated very quickly after calling in a missile strike.
14 Ego the Living Planet
It was shocking when James Gunn announced that Ego the Living Planet would be Star Lord's father in Guardians of the Galaxy Vol. 2. After all, Ego, in the comics, is nothing more than a sentient planet. However, he had a lot of power that allowed him to face cosmic beings like Galactus. He even died and came back to life.
In the movie, though, Ego took a much different origin. He is one of the Celestials of the MCU. However, he wanted to take control of the entire universe by planting seeds on numerous planets so that he could grow and expand. He also wanted to have a son to complete his quest for power, and that's how he ended up falling for Star Lord's mom (if you could call it "falling," that is).
13 The Chitauri
Most people who recognize the Chitauri will remember them as the army that attempted to destroy New York in The Avengers. Apart from having some flying jet skis and giant worms, there wasn't anything to differentiate them from other bad guys. They could've been just about anything, and the movie wouldn't have changed a single bit.
In the comics, the Chitauri were a bit more defined. They were a variant of the Skrulls, classic Marvel comics villains who had powers like shape-shifting and adaptation. The Chitauri were simply the Ultimate Universe equivalents of the Skrulls, complete with their various powers. However, Marvel felt that instead, they just needed an army for the Avengers to fight.
Ultron is one of the biggest villains of the Avengers. After originally being created by Hank Pym, Ultron eventually became autonomous and went out on his own. After taking the guise of the Crimson Cowl, it was revealed that he was indeed the robot Ultron, and he had a desire to purge the world of humanity. He was terrifying, aloof, and held all of the powers you'd expect from such a robot.
In Avengers: Age of Ultron, Ultron was a failed experiment created by Tony Stark. This robot became autonomous but wasn't as terrifying as he was in the comics. Instead, he was like a dark version of Tony Stark, complete with all of the jokes and quips you'd expect from the MCU. It was a far cry from how menacing the character originally was.
Guardians of the Galaxy defined those characters in the Marvel Universe. Nobody cared about them or knew who they were until the movie hit theaters and was massively successful. Marvel took the opportunity to redesign the Star-Lord character after how the movie portrayed him. The problem with this is that nobody will ever know who he was beforehand.
Before the movie, Star-Lord was the calm and collected leader of the Guardians. He held a very official uniform and protected the law rather than defied it. He even earned the respect of the other members of the Guardians as well as the Avengers. After the movie, his outfit, personality, and impact were all given a major overhaul.
10 The Mandarin
Most of the people who watched Iron Man 3 and loved it probably have no knowledge of the comic books. While the movie was fairly well received by critics, the fans and the audience had a different opinion. That was largely due to how the villain, the Mandarin, was handled in the movie.
For those of you who aren't familiar, the Mandarin is the archrival of Iron Man. Ever since Iron Man in 2008, it was teased that the big bad would make an appearance. With the use of his ten rings, he was also one of the strongest baddies in the Marvel Universe. Unfortunately, Iron Man 3 did the character a horrible injustice. It turns out that the terrifying Mandarin that was shown in the trailers was simply a ruse, and it was all just an elaborate joke.
9 The Ancient One
A fairly recent change that was made in the MCU was found in Doctor Strange. In the film, Stephen Strange found a magical facility that was led by a powerful sorceress known as the Ancient One. This elderly woman had a great knowledge of the mystical arts and did everything she could to protect the various sanctums from dark magic (even going as far to draw power from the Dark Dimension herself).
However, in the comics, the Ancient One was a much stronger-appearing male figure. He was old, wise, and chose Stephen Strange for a reason. Instead of denying the character entrance, the Ancient One specifically trained Strange to become the new Sorcerer Supreme. If that plan failed, he also had a few backups in store. Nonetheless, this was a big change that caused a bit of controversy with fans.
8 Scarlet Witch and Quicksilver
Rocketing off the Ultron argument, Scarlet Witch and Quicksilver were also given severe changes to fit in with the MCU. They, too, appeared in Age of Ultron as kids who were voluntarily experimented on and given powers. They originally fought against the Avengers, but after they realized who Ultron was, they switched sides. Since then, they've become official members of the team (Quicksilver is probably just an honorary member).
In the comics, Scarlet Witch and Quicksilver were the twin children of Magneto. They had big ties with the Brotherhood of Evil Mutants before deciding to become Avengers. Furthermore, Scarlet Witch's powers were much more dangerous than the MCU depicts them. When placing enough effort, she could even alter reality itself. In the movies, she's a much watered down version of herself.
7 Iron Man's Personality
Ever since Robert Downey Jr. played Tony Stark, that character has never been the same. Everyone now pictures him as a playboy billionaire philanthropist. What many people don't know is that this personality we see in the Marvel movies is nothing like what he originally was in the comics.
Sure, he struggled with the occasional alcoholism, but Iron Man was much more refined than the movies will have you believe. He was brilliant and put his time and effort into growing his business as well as bettering his Iron Man technology. He wasn't arrogant and didn't bring all kinds of problems to everybody he knew. Instead, he was calculated, helpful, and even went out of his way for other people.
6 Pepper Potts
Pepper Potts is most known these days for being the assistant and eventual girlfriend of Tony Stark. In the Iron Man films, she had an origin very similar to the source material. However, it's after that point where things start to differ. She ends up becoming the CEO of Stark Industries before moving on to other things. Yet, she still seems somewhat incapable at the end of the day.
In the comics, Pepper Potts ends up helping out several organizations and even has her own codename. She's also used her own variant of the Iron Man suit a few times to help out. Considering that modern-day audiences are desperately craving stronger female representation, it seems like it was a missed opportunity for Marvel.
Ant-Man has been a big part of the Avengers ever since they were originally created. It makes sense, then, that the character would be a part of the MCU. However, there were some big alterations made in this continuity to fit the timeline and the tone.
Despite being one of the founding members of the Avengers, Ant-Man didn't appear until the end of Phase 2. Furthermore, it wasn't Hank Pym who ended up wearing the suit, but Scott Lang (the second Ant-Man in the comics). Hank Pym did appear in the film, but his time as the Ant-Man only took place in the World War 2 era, when Howard Stark and Peggy Carter were running SHIELD. He has yet to interact with the Avengers, and we're sure that he never will.
4 Founding of the Avengers
The Avengers was put together for a purpose: to bring together Earth's Mightiest Heroes to fight bigger battles. Marvel did it as a means of putting iconic characters into one story. The original team was composed of Thor, Hulk, Iron Man, Ant-Man, and the Wasp. They worked together to battle the tricks of the god of mischief, Loki.
In The Avengers, the team was put together by SHIELD and Nick Fury. The original members were Thor, Iron Man, Hulk, Captain America, Hawkeye, and Black Widow. While they fought the same villain (Loki), they also had to take down an army of Chitauri and send a nuclear bomb into a weird space portal. It's definitely a more modern take on the old story.
3 Hulk and Black Widow
Many movies these days just throw romance together because they think it's interesting, and apparently, Marvel isn't above this trope. In Age of Ultron, we see Hulk and Black Widow somehow establish a connection that had no previous buildup. She seemed to be the only one who could bring him out of the "Hulk mode," but there was no explanation for it. We, as the audience, were just meant to accept it and move forward.
In the comics, a plotline like this never occurred. Hulk and Black Widow remained separate and didn't establish a romantic connection. The biggest love interest that the Hulk had was on his planet Sakaar. It was there that he married a woman and even had a child before it all went to hell.
2 No Lasting Deaths
Despite the lighthearted image it gets, Marvel Comics have been known to kill characters off to shake up the continuity. As a matter of fact, they were the ones who set the stage for comic books to kill characters off (with the death of Gwen Stacy). Since then, they've had brutal arcs that involved the death of someone important like Dark Phoenix Saga.
In the MCU, this isn't the case. Agent Coulson died in The Avengers but was weirdly brought back for Agents of SHIELD. Bucky Barnes died in Captain America: The First Avenger but was brought back in Captain America: Winter Soldier. The only superhero who really died was Quicksilver, but he wasn't in the MCU long enough for us to feel extremely sad about it.
1 Civil War
Never has a comic movie been so different from the source material than with Captain America: Civil War. The movie has an incident take place in Sokovia, which motivates the United Nations to request that the Avengers report to the government. Cap and Stark take different sides, and their disagreements eventually lead to an all-out brawl.
That's where the similarities end, though. Captain America: Civil War isn't solely about the conflict. The Civil War comic is. In it, Cap puts together a team of Secret Avengers while Stark and his fellow ego-heads get a team of heroes and villains. Just about every Avenger imaginable is there for the conflict. The lines are drawn, the battles are fought, and some heroes even die as a result.
Sources: MCU, Marvel Comics