The X-Men have a lot on their plate—not only do they have to protect a world that hates and fears them, but they also have to protect themselves and mutant-kind from that world. The X-Men have faced down all manner of powerful villains over the years in their quest for survival and acceptance and face some of the most intriguing villains any comic team has ever encountered.

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Meanwhile, the Avengers are Earth's Mightiest Heroes who come together to face threats that no one hero can face on their own. The Avengers have tackled some of the evilest beings in the Marvel Universe. Their enemies have included some of the biggest threats to life ever known and it's a miracle that the Avengers can save the day against them.

10 X-Men's Villains: Very Sympathetic

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One of the things about the X-Men's villains that sets them apart from the enemies of other teams is that they aren't often cackling, take over the world types. Instead, many of them are just mutants who are fighting against the oppression of humanity, doing their best to combat the racism that affects their daily lives.

This makes many of them extremely sympathetic and, ironically, humanizes them. Readers can understand why the X-Men's villains are doing what they are doing and sometimes can even empathize with them. For many of these villains, the line between hero and villain is extremely thin.

9 Avengers' Villains: The Biggest Heroes Need The Biggest Villains

Avengers Villains Header

The Avengers are an assemblage of some of the greatest heroes in the Marvel Universe, ones who are experts at working solo. The Avengers were brought together to defeat enemies they couldn't handle on their own and as the years have gone on, the team has only grown in numbers and powers. With a group like the Avengers, they need to battle threats that challenge them and the team's villains accomplish this.

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The Avengers have faced down some of the most powerful villains the Marvel Universe has to offer. Other teams face big threats, but the Avengers are the first and last defense against the villains who are often extinction level events.

8 X-Men's Villains: The Sentinels

Sentinels Attacking

The X-Men have to deal with lots of things that most other groups of heroes don't have to deal with, like the government trying to exterminate them because it's Tuesday. To do this, the government, and sometimes just anyone with enough money, mobilize the Sentinels, dangerous mutant-hunting machines.

Sentinels are an interesting foe because in every future where they run amok, all heroes are targeted and exterminated by them, with the Sentinels eventually taking over humanity to make sure no mutants are born. In the present, the X-Men are the only thing keeping the world from this dystopia, protecting humanity from the consequences of their racism.

7 Avengers' Villains: The Masters Of Evil

Masters Of Evil

When a team is as powerful and skilled as the Avengers, sometimes one villain just won't cut it against them. This is where the Masters Of Evil come in. This villainous team has been through a lot of permutations over the years, including some of the greatest villains that the Avengers have ever faced.

There have been no teams that have given the Avengers such trouble over the years as the Masters Of Evil. In fact, the Masters Of Evil has been responsible for some of the Avengers' greatest defeats, managing to take away their headquarters and brutalize the team in ways that few of their foes have.

6 X-Men's Villains: The Brotherhood Of Evil Mutants

Magneto and the brotherhood of evil mutants

Much like the Avengers, the X-Men have had their own team of villains to face—the Brotherhood of Evil Mutants. Brought together by Magneto, the team has been through a lot of changes over the years and had some extremely powerful members. While they have the same goals as the X-Men- freedom from persecution for mutants—their methods have been wildly different.

These methods have also differed wildly between incarnations, as well. Magneto's group was all about mutant supremacy. Mystique's found its way to government work as a method of getting mutant recognition. Daken's group existed just for him to take revenge against Wolverine. The Brotherhood is different every time the X-Men encounter them.

5  Avengers' Villains: Protecting The Earth From Invasion

Marvel's Avengers in the Kree-Skrull War.

While both the Fantastic Four and X-Men have dealings with aliens and have protected the Earth from them, the Avengers have been the ones to mostly deal with the widespread attacks alien races have made on the Earth. The team is uniquely qualified for this; they have members from every corner of the Marvel Universe.

These aliens villains have challenged the Avengers as much as any other foe they've ever faced; from Skrull Queen Vernake to Ronan the Accuser to all kinds of other aliens trying to take the Earth, the Avengers have faced all manner of alien villains bent on conquering the Earth.

Magneto threatening people in front of a tree

There's something about the best X-Men villains; fans love them. Take Magneto, for instance. Magneto is pretty much the ultimate sympathetic villain. He grew up in the Holocaust and his hatred of humanity is actually pretty valid. Creators have done a lot with the character and fans love Magneto so much that's jumped the line between hero and villain many times, even being a member of the team for over a decade now.

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Magneto isn't the only X-Men villain who has joined the team either, as villains like Sabretooth and Mystique have joined the team and one of the most popular members, Rogue, began life as a villain. The X-Men's villains are so interesting and beloved that they demand a bigger spotlight and that's often as a hero.

3 Avengers' Villains: Creating Their Own Bad Guys

Marvel Comics Kang And Ultron

Two of the Avengers' best villains, Ultron and Kang the Conqueror, wouldn't exist without the team. Ultron was literally created by an Avenger—Hank Pym created the android as a lab assistant but when it gained sentience, he tried to destroy the android, sparking its hatred for humanity. Ultron would become one of humanity's greatest threats and all because of the Avengers.

While Kang wasn't created directly by the Avengers, he only came back in time to prove himself against the most formidable foes he can think of, the Avengers. The best villains are linked to the heroes they face and the Avengers have links to two of the most dangerous villains around.

2 X-Men Villains: The Oldest Villain Of Them All—Humans

X-FORCE - Anti-Mutant

The X-Men's greatest villain isn't some costumed person with superpowers. It isn't some genocidal machine or a mutant trying to destroy humanity so mutants can live without fear of death. The X-Men's greatest foes are the human race and the racism humans have towards mutants. This isn't a foe they can punch into submission; it's not even one they can beat.

The X-Men's greatest battle isn't saving the Earth but simply surviving the racism of the human race, which is something that many of the X-Men's readers can understand. This battle makes the X-Men one of the most important teams in comics, as they face a foe that people in the real world understand- human bigotry.

1 Avengers' Villains: The Last Line

Thanos Is Kronos' Grandosn

The Avengers exist to take on the biggest threats. When Thanos comes calling, the Avengers are the ones who organize the resistance. When Ultron tries to exterminate humanity, the Avengers stop him. When the Beyonders decided to destroy the Multiverse, the Avengers were there. Evil gods? The Avengers. Celestials? The Avengers.

The thing about Avengers villains is that while they have their own foes, they also face the foes of other heroes when things get out of hand. This means that any enemy who poses a big enough threat can be a foe of Avengers, giving them access to some of the greatest villains ever.

NEXT: Avengers: 10 Heroes Who Died In The Infinity Gauntlet