The Avengers are Earth's Mightiest Heroes. They're also the most principled team in the Marvel Universe. It's one thing to save the day, but there are levels that the Avengers aren't supposed to go to. They're the best and the brightest, the heroes that everyone looks up to. They're supposed to be the paragons, which is why it's so disturbing when they break their own rules. They're the shining example of heroism, and when they fall short, it means something.

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Heroes are supposed to comport themselves a certain way, especially when they're of the Avengers' stature. When they don't, for whatever reason, it hurts all the other heroes, changing the way the world looks at them.

10 Iron Man Had Wolverine Join The Avengers Specifically Because He Killed People

Iron Man offering Wolverine membership on the New Avengers in 2005's New Avengers #6

Wolverine and Captain America fought once in the past. Cap specifically told Wolverine he'd never be allowed to be an Avenger because he was a killer. However, Wolverine would famously become a member of the Avengers during the New Avengers years. The reason was that Iron Man figured the team needed someone willing to kill.

Iron Man is a habitual line stepper when it comes to breaking Avengers' rules. That's not to say that Wolverine wasn't a good Avenger or that he shouldn't have been on the team, but Iron Man put him on the team specifically because he was willing to break the rules.

9 Iron Man And The Illuminati Did Terrible Things During The Incursions

The Illuminati fighting the Great Society

Iron Man rarely met an Avengers rule that he wouldn't break. Forming the Illuminati was bad in general, but it wasn't until the Incursions that the team flaunted Avengers rules in the worst way. The Illuminati began to destroy the Earths that were about to collide with the 616 Earth, and they even mindwiped Cap when he objected.

The argument can be made that they did what was needed to save the universe, but a team with the most intelligent people on Earth should have been able to come up with another way. Regardless of the circumstances, they committed genocide on a massive scale.

8 They Were Hypocrites About The Phoenix Force

Marvel's Echo Maya Lopez with the Phoenix Force

Echo is the new host of the Phoenix Force and a member of the Avengers. This is a very ironic turn of events considering what happened the last time the Phoenix came to Earth. The Avengers, at Wolverine's behest, attacked the X-Men, causing a conflict that wouldn't have even happened if they had stayed out of it.

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When the Phoenix came to the Avengers, they fought in a contest for it instead of trying to stop it from getting to Earth like they did before. They even allowed someone to have it who had no preparation or experience with it. It was massively hypocritical.

7 They Never Actually Tried To Help Scarlet Witch

Scarlet Witch reading the Darkhold in Marvel Comics.

The Avengers are all about helping one another. The team looks out for its own, but they make mistakes. For example, the team basically kept Scarlet Witch safe from the consequences of her actions instead of trying to get her help. They actively made things worse for her by mindwiping her memory of her children. They did everything to keep her from punishment, even when she was villainous.

The Avengers looked out for her, but they never really helped her. This only exacerbated the situation with her, allowing her to get away with everything she did. The Avengers are supposed to help each other, but they failed miserably with the person that needed it the most.

6 They Cozied Up To The Inhumans After The Release Of The Terrigen Mists And Ignored Mutant Plight

Thanos looking on as Black Bolt activates the Terrigen Bomb in Marvel Comics.

Black Bolt's detonation of the Terrigen bomb had major repercussions. The Inhumans grew like never before, as many humans carried Inhumans genes. The race became a power in the world like never before, and the Avengers ended up cozying up to them. However, the release of the Mist was terrible for mutants, causing the X-Men to move their operation to Limbo while relocating mutants there.

The Avengers were kept pretty mum about the plight of mutants during this time. Other than the Avengers Unity Squad, which added Inhumans to the mix regardless of what their race was doing to mutants, the Avengers didn't care what happened to mutants.

5 The Avengers Attacked The X-Men First

The Avengers battling the X-Men in Marvel Comics

The Avengers' conflict with the X-Men was a major violation of the team's rules. With the Phoenix Force incoming, Cyclops had a plan to use it to jumpstart the mutant race. Wolverine, having taken half of the remaining mutants with him after an ideological disagreement with Cyclops, badmouthed him to the Avengers, causing the team to mobilize against the Utopia X-Men.

Instead of giving the X-Men, who were much more experienced with the Phoenix, the benefit of the doubt, they enforced their will with the team. They went so far as to take an aggressive stance first, violating mutant sovereignty. It was something the Avengers never would have done before and actively tried not to do with heroes that were ostensibly their allies.

4 Thor Killed The Sentry

Thor vs Sentry

The Sentry was as frightening an Avenger as they come, both because of his massive power and the fact that he was also the Void. After Norman Osborn took over the Avengers, he used the composite entity as his boogeyman. This eventually came back to bite him, as the Void took over and threatened the entire world.

The real Avengers stood against the monster and were finally able to get the Void to go away for a moment. The Sentry begged Thor to kill him, and the God of Thunder did so. Avengers aren't supposed to kill, no matter the circumstances, and there were powerful heroes there who could have put the Sentry in stasis until they figured out how to save him.

3 Iron Man Stood With The US Government Instead Of His Teammates

An image of the Avengers divided over Civil War

Iron Man got shadier and shadier as the years went on, and his actions in the superhero civil war stand in direct opposition to how he acted before. The US government had tried multiple times to take control of the team, and they all fought against it, including Iron Man. While the disaster at Stamford changed everything, Iron Man's willingness to cave and betray many of his teammates was a one-eighty.

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The superhero civil war led to widespread destruction, the deaths of several heroes, and drove a wedge into the hero community. The scars from it took years to heal, and it left the world weaker than it was before. All of this can be placed squarely at Iron Man's feet, along with any Avenger who sided with him.

2 The Avengers Took Command Of An Intergalactic War And Left The Earth Open To Attack

Thanos in the Avengers Infinity comic grinning evily.

The war against the Builders and their forces was a harrowing affair, one that saw the Avengers take command of the forces of multiple intergalactic empires. On the one hand, this is definitely a bit of Avengers rule-breaking, as the team taking command of forces out to kill other beings is a violation of the team's no killing rule indirectly. On the other, it was what turned the tide in the war.

The entire team left the Earth, except for the few members of the Illuminati and members affiliated with other teams, leaving the team open to assault from Thanos. The Avengers protect the universe, but the Mad Titan ran roughshod over the Earth while they were away, doing massive damage.

1 Avengers Killed The Kree Supreme Intelligence

The Avengers during Operation Galactic Storm split image

"Operation: Galactic Storm" saw the Avengers inject themselves into the war between the Shi'Ar and the Kree. Thanks to interference by the Supreme Intelligence, the Kree were destroyed by a Skrull Nega-Bomb that was given to the Shi'Ar. The Supreme Intelligence meant for this event to jumpstart Kree evolution, but it earned him the ire of the Avengers.

The team debated what to do next, with a portion wanting to go home because the war was over. Others wanted revenge against the Supreme Intelligence. This group went to his wrecked citadel and confronted him, eventually killing him for his crimes.

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