The Avengers have defended the Earth – and the galaxy – time and time again, and have never backed down from a threat, no matter how high the stakes. With some of the most powerful heroes among their ranks, it's hard to imagine anything that could strike fear into Earth's Mightiest Heroes.
And yet, plenty of secrets, superstitions, and scandals have rocked the Avengers to their very core. After years of fighting the good fight, there have been several occasions when the team has seen some of their greatest fears come to life.
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Wanda Maximoff's Mental Breakdown
After almost twenty years, Wanda Maximoff's breakdown is still discussed among the Avengers faithful. The Scarlet Witch's descent into madness which caused both the Avengers Disassembled event of 2004 and the House of M event of 2005, is still one of the most infamous moments in Avengers history.
To see one of their own suffer so much, and snap so profoundly scarred the Avengers for years. It's hard to imagine a team that claims to treat itself like a family suffering so much at the hands of one of its members, especially considering how the signs were all there pointing toward's Wanda's mental decline.
9 The Avengers Neglected the Mutants for Years
Despite claiming to be Earth's premiere defenders, it is staggering to consider the little-to-no effort the Avengers have made to improve mutant-human relations. Especially considering the many close relationships between the X-Men and the Avengers, one would have expected the Avengers to have done more for the mutants.
This became a key point of conflict for the Avengers when the Phoenix Force returned to Earth in the Avengers Vs. X-Men event. Wary of the Phoenix's destructive power, the Avengers sought to destroy it, while Cyclops and the X-Men believed in its ability to save mutantkind through its intended host, Hope Summers. The resulting conflict would indefinitely change the relationship between the Avengers and the X-Men.
8 Hank Pym Merged With Ultron
Hank Pym is one of the founding members of the Avengers, and one of the more infamous team members. One of Hank's most regrettable moments on the team was his creation of Ultron, the sentient AI that would evolve into one of the Avengers' greatest foes.
The twisted father-and-son dynamic between Pym and Ultron has long been explored, taking on a new approach in Avengers: Rage of Ultron. After nearly killing the Avengers, Ultron then fused with Hank Pym before disappearing, seemingly taking Pym's life.
7 Time Runs Out Pitted The Avengers Against Each Other
For a team that has worked together for decades, considers themselves family, and prides itself on the trust and connection they share with their fellow members, the Avengers spend a large amount of their time fighting each other. Jonathan Hickman's Time Runs Out event pitted the Avengers against each other, completely destroying their trust in one another.
After learning that Iron Man and the Illuminati had wiped his mind, Captain America and his Avengers committed themselves to hunting down the Illuminati, while the end of their universe quickly approached. It was far from the proudest moment in Avengers history, with all that the team is meant to represent being cast aside.
6 The Avengers Would Disband
The Avengers have faced countless threats, each one more gruesome, dangerous, and nerve-wracking than the last. Between world-ending disasters, time-traveling warlords, and alien invasions, the team has stood together in times of crisis.
But that wasn't the case during the Avengers: Disassembled event. In what was described as "the worst day in Avengers history," the Scarlet Witch's chaos magic led to the death of several team members, the destruction of Avengers Mansion, and the eventual disbanding of the team altogether. Despite their resilience and togetherness in the face of chaos, the Avengers failed to rise to the challenge.
5 The Team Couldn't Trust Each Other
A team like the Avengers is only as strong as its members' trust. With the dangerous situations the team finds themselves in, they cannot risk not being able to trust their teammates, as their lives very much depend on it.
The Skrull Invasion during the Secret Invasion event turned all the Avengers against each other. Without any way to truly know who was and wasn't a Skrull, a whole new level of paranoia and in-fighting settled into both the New Avengers and the Mighty Avengers. All a part of the Skrulls' strategy to conquer the planet.
4 The Avengers' Name Was Dragged Through The Mud
When they first joined forces, the Avengers did so out of the need to defend the Earth from danger. However, after decades of protecting the planet, the Avengers have become an institution, a force of good that embodies justice, honor, and righteousness. The reputation of the Avengers is sacred, and its members lay their lives on the line to honor it.
However, when Norman Osborn created his own team of Avengers, he enlisted the help of known supervillains and murderers to pose as famous Avengers. With Moonstone, Daken, and Bullseye posing as Captain Marvel, Wolverine, and Hawkeye, respectively, the reputation the Avengers had sacrificed so much for was tarnished.
3 The Hulk Has Gone Out Of Control
An original member of the Avengers, the Hulk is possibly the strongest Avenger there is. Of course, a key part of his strength is the rage that fuels it, and with all the rage that consumes the Hulk, it's not uncommon for him to lose control of himself. The Avengers have always been aware that the cost of having the Hulk on the team is high, should he lose control and become a threat to the safety of others.
Unfortunately, that has happened on several occasions. Whether it was a result of meddling from the Avengers' foes, or simply the Hulk himself losing control, the gamma giant has destroyed cities, killed civilians, and has come to blows with his teammates many times.
2 They Turned Wonder Man Against Them
Simon Williams has been named among some of the strongest Avengers. Originally recruited by the Masters of Evil to infiltrate the Avengers, Wonder Man ended up joining the Avengers properly. But over the years, he became unimpressed and frustrated by the team's infighting and lack of conflict resolution skills.
Eventually, Williams grew unstable and violent, and even attacked the Avengers after recruiting a number of vigilantes who also felt they had been scorned by the Avengers. Though he was stopped, Wonder Man's rage was initially well-placed, as he plainly criticized the Avengers' part in several global conflicts.
1 The Avengers Created A Doomed Reality
A constant conundrum that the Avengers have tried to solve, Ultron has forever posed a threat to humanity. Because of its ever-evolving superior AI, the Avengers decided that to stop Ultron from ruling over humankind, the only solution left was to go back in time and kill Hank Pym, stopping Ultron's creation.
However, after Sue Storm and Wolverine killed Hank Pym in the past, they returned to their present to find that instead of Ultron ruling, Doctor Doom and Morgan Le Fay were in a conflict that doomed them all. This meant they had to stop themselves from carrying out their original plan, causing considerable complications to the timestream.