In the Marvel Universe, there is no team of superheroes given more respect than the mighty Avengers, who earned the title of "Earth's Mightiest Heroes" through ingenuity, brute strength, team work, and the pursuit of the greater good. The Avengers have stayed true to that goal since their conception in 1963, and continue to stand by the principles they were founded on.

The Avengers have vanquished some of the most powerful foes in the Marvel Universe. Some were time-traveling warlords like Kang the Conqueror, and others were enemies of their own creation, like Ultron. Though the Marvel Universe certainly wouldn't be the same without them, they're not the only superhero teams that people depend on.

There's also the Fantastic Four, the X-Men, and the Defenders who have contributed more than their fair share when it comes to saving the world. Though they all share the same goal, getting along and sharing details isn't always part of the process. Sometimes there's mix-ups and differences of opinions, which lead to epic clashes and some serious bruises. Egos can get bruised too. Do Earth's Mightiest Heroes always come out on top? Let's have a look at 15 Times The Avengers Fought Other Superhero Teams.

15. Justice League of America

JLA Justice League Avengers Crossover Comic

JLA/Avengers was a Marvel and DC comic book crossover published in 2003 through 2004. At the beginning of the crossover, two powerful cosmic beings—Grandmaster of the Marvel Universe and Krona of the DC Universe decide to play a game for the fate of the Marvel Universe. Grandmaster chose the Justice League of America as his champions while Krona chose the Avengers. As the two teams collided, Batman and Captain America realized that something bigger than them was at stake and decided to solve this mystery together. Meanwhile, the JLA and the Avengers fought all over the world, giving readers a chance to see Superman defeat Thor, Green Lantern face off with Wonder Man, and Hercules exchange blows with Wonder Woman.

The Justice League were winning, until the final battle which took place on the Avengers' Earth. Without the Speed Force, Quicksilver was able to easily outrun and defeat Flash, which would have tied the score, but at the very last second, Batman and Captain America intervened and kept Krona from obtaining a victory.

Furious, Krona found a way to alter reality, forcing the Avengers to team up with the JLA to restore reality.

14. The Invaders

During World War II, a group of superheroes called the Invaders helped the Allies fight the Nazis. Among these heroes were Captain America, Bucky, the Human Torch, Toro, Namor the Sub-Mariner, and Union Jack. In 1943, the Invaders were caught in a strange green mist that hurled them forward in time. As word spread, Iron Man feared that their presence could endanger the timeline and led the Avengers on a mission to capture them. Following him into battle were Ms. Marvel, Ares, Wonder Man, Sentry, and Black Widow.

The two teams fought it out for a while, but in the end the Avengers were victorious, as they outmatched the Invaders in raw power. The Invaders' strongest member, Namor, was the only one capable of escaping them. The Invaders were later freed by Luke Cage's team of Avengers.

When the Red Skull got his hands on the Cosmic Cube, both teams of Avengers with the addition of the Invaders had to work together to defeat him.

13. The Thunderbolts

The Thunderbolts—Songbird, Radioactive Man, Speed Demon, Joystick, Photon (Genis-Vell), and Atlas—were a group of reformed villains working for the government in exchange for parole. They were sent on a mission by the U.S. government to fight the New Avengers. The mission was not only to defeat them, but to humiliate them. The order came at a time where the Avengers had been decimated by the reality-warping powers of Scarlet Witch during Avengers Disassembled. Cap had to put together a new team of heroes, consisting of Luke Cage, Iron Man, Spider-Man, Sentry, and Spider-Woman. The Thunderbolts were unclear on why they would be given such an order, but their desire for parole proved motivation enough.

The Thunderbolts ambushed the Avengers and hit them with everything they had. Each of the Avengers were now convinced that the Thunderbolts had returned to their criminal ways. Considering that the Avengers were armed with the tactical mind of Captain America and powerhouses like Sentry and Iron Man, the odds seemed to be in their favor. However, things went south fast. Luke Cage was taken out early, giving the advantage to the Thunderbolts. Somehow, each Avenger was thoroughly defeated. It ended with Songbird telling them that they could do this to them again at any time they pleased. This was not one of the Avengers' finest moments, and one Cap would love to have erased from memory.

12. The Inhumans

After the Inhumans moved their ancestral home to the Moon, the U.S. government discovered their presence and sent the Avengers to determine if they were a threat. The meeting between the two groups allowed the Avengers to reunite with their former teammate, Quicksilver, who was married to Crystal, sister-in-law of Black Bolt.

The Avengers were friendly to one another until missiles were launched from the Moon to strike Earth. After Thor struck down the missiles, the Avengers became suspicious of the Inhumans. That was when Black Bolt shocked them all by ordering the Avengers to be executed. A fierce battle erupted as Starfox fought with Triton, Scarlet Witch went up against her brother's wife, Captain Marvel (Monica Rambeau) tested her speed against Quicksilver's, Captain America fended off the attacks of Lockjaw, Vision battled Karnak, and Gorgon was knocked out by She-Hulk. The battle came to an end when Medusa challenged Black Bolt's order and discovered that "Black Bolt" was actually his brother Maximus in disguise.

11. Starjammers

During the Kree-Skrull War, the Avengers found the head of the Kree Empire, the Supreme Intelligence, who had caused the deaths of millions. The Avengers were split over whether or not it was morally acceptable to kill him. Iron Man gathered a group of Avengers who felt that killing the Supreme Intelligence was the right thing to do, and the Black Knight was the one who made the killing stroke. No Avenger could have predicted the repercussions.

Soon after the Avengers returned to Earth, they were visited by the Starjammers, a team of space pirates led by Corsair, the father of Cyclops. Neither group was aware that one of the Starjammers, Raza Longknife, was manipulated by the Kree into believing that his dead son was still alive, and that they would reveal his location if he were to avenge the Supreme Intelligence and kill the Black Knight. Reluctantly, Raza agreed and attacked the Knight. Unable to defeat him, Raza had to threaten Crystal's daughter in order to strike him down.

The result was a showdown between the Avengers and the Starjammers, with Hercules going wild. Eventually, Starjammer and former Avenger Carol Danvers was able to diffuse the situation. Black Knight recovered from his wound and the Starjammers returned home.

10. X-Men (1987)

The X-Men fight the Avengers in Marvel Comics 1987 limited series.

In 1987, Magneto was the leader of the X-Men, per the suggestion of Professor Xavier himself, who wholeheartedly believed that the Master of Magnetism had changed his ways. The Avengers, however, had recent encounters with Magneto and had little reason to believe that he had reformed. When the Soviet Union wanted Magneto assassinated for sinking a Russian submarine, the Avengers decided to arrest him so that he could go to trial. After the X-Men and the Avengers worked together to fend off a team of Russian superheroes, the two teams clashed over the fate of the Magneto.

Black Knight fought Wolverine, She-Hulk fought Rogue, Captain Marvel (Monica Rambeau) fought Havok, and the rest dealt with Magneto. The fight was interrupted by an explosion before any outcome could be determined. Later, Magneto used a device to prove what he always believed: that all humans shared anti-mutant sentiments. After using it on Captain America, he was overcome with shame when he realized that Cap's heart was free of prejudice. This caused Magneto to surrender, making this the Master of Magnetism's first step toward a sincere change.

9. The Rangers

As Hawkeye was building up his team of West Coast Avengers, there was one hero he desperately wanted on the team: the Thing. Tired of being "nagged" by Hawkeye, the Thing continuously declined his invitation. While Hawkeye focused on recruiting the Thing, he neglected another hero who did want to join: Firebird. When Firebird realized that Hawkeye wasn't going to ask her, she put in a call to her old team, the Rangers, a group of heroes based in the West. The Rangers consisted of Texas Twister, Shooting Star, Red Wolf, and Phantom Rider.

When the Rangers arrived, Firebird sensed that Shooting Star was possessed by an evil force. The accusation caused the two teams to break out into a fight, one that the West Coast Avengers easily won in a series of one-on-one matchups. The Avengers learned that Shooting Star was actually a demon, and that the attack on the Avengers was a plot engineered by Master Pandemonium.

8. Freedom Force

The main Avengers team and the West Coast branch were having their annual baseball game when Mystique, Blob, Pyro, Spider-Woman (Julie Carpenter), Destiny, Spiral, and Avalanche showed up unannounced. Most of them were known to be X-Men villains but were apparently doing work for the government under the name, "Freedom Force." Mystique declared that the Avengers were under arrest but would not say why. Torn over whether they should surrender or fight, the Avengers were in the process of making a decision when Hercules made it for them by throwing a pitchers' cart at Freedom Force.

While the two teams fought, Cap left to call the government. Despite the Avengers' advantage in numbers, Freedom Force managed to overcome the odds using sneak attacks and mind-blasts to weaken the Avengers' most powerful members. In the end, it was down to Wonder Man, who fought them off for as long as he could until Destiny blasted him from behind. It was then that Captain America showed up and surrendered, after confirming that the warrant for their arrest was official.

Later, the Avengers escaped and learned that they had been set up by Quicksilver, who had been manipulated by Maximus. After his defeat, the Avengers sent him back to the Inhumans.

7. X-Men (1968)

When Magneto captured the X-Men, he created a device that would allow him to psychically weaken their mental resistance enough for him to control him. Angel escaped and managed to warn the Avengers. When the Avengers arrived to face Magneto, Magneto unleashed the X-Men on them. Ice-Man and Hawkeye had a long-distance battle of ice and arrows, while Beast and Black Panther, two of Marvel's most agile heroes, tested each other's acrobatic skills. Giant-Man had to overcome the disadvantage of being an easy target for Cyclops' optic blasts, and Wasp had to maneuver out of the path of Jean Grey's telepathic attacks.

The Avengers managed to defeat the X-Men without any of their own falling in the fight. When the X-Men regained control of their senses, they joined forces with the Avengers to pursue their captor. As Magneto tried to escape, the evil villain was left behind by his mutant underling, Toad, and seemingly perished in an explosion.

6. Squadron Supreme

The Squadron Supreme is a team of superheroes from another universe who were based off popular DC Comics characters. They were sent by the President of the United States of their world, under the control of the Serpent Crown, to capture the Avengers. After the Avengers were beaten and locked up in a facility, they managed to escape and steal the Crown. The Squadron Supreme vowed to find them and split off into small groups.

Of all the battles that took place, none was more notable than the one between Vision and three members of the Squadron. In order to protect Scarlet Witch who was holding the crown, Vision defeated Lady Lark, Golden Archer and the Squadron's most powerful hero, Hyperion, who was created to be the equal of Superman.

When the fighting was over and the Avengers were victorious, the Beast used a trick to make the Squadron Supreme realize their mistake.

This storyline is especially memorable as it was during this adventure that Patsy Walker became the costumed hero, Hellcat.

5. Fantastic Four

When Hank Pym was leading a new team of Avengers in 2009, he wanted to build a virtual heaven using Pym Particles but needed a device invented by his former assistant, Bill Foster, who had been killed by the cyborg Thor in Civil War. Since Pym was off-world at the time of Foster's death, the device fell into the possession of Reed Richards. Since the device was built using Pym's research, and also since Pym knew that Foster would have wanted Pym to have it anyway, Pym asked Richards to return it. Much to Pym's surprise, Richards refused. When asked for an explanation, Richards spoke eight words that sparked an all-out slugfest between the Avengers and the Fantastic Four: "I know more about Pym Particles than you."

Pym devised a plan to invade the Baxter Building and sent the Avengers into battle, pitting Hercules against the Thing and the Vision against the Human Torch. After a battle of wits between Pym and Richards, Richards changed his mind and handed the device over to Pym.

4. X-Men (2012)

Avengers VS X-Men

Years after the death of Jean Grey, the Phoenix Force chose a new host: a young mutant named Hope Summers. Aware of her destiny, the X-Men were providing her shelter. Cyclops had the idea that if she could control the Phoenix Force, she could become a mutant messiah. When the Avengers discovered that the Phoenix Force was on its way to earth to claim Hope as its host, they knew action had to be taken.

Captain America told Cyclops to hand Hope over to them so that they could keep her away from the Phoenix Force. Cyclops' refusal ignited a war between the two teams. The Avengers and the X-Men fought all over the world, from the Savage Land to Wakanda. Things went from bad to worse when the Phoenix Force split into five pieces and bonded with five of the X-Men. The Avengers had to team up with the remaining X-Men to stop them. Most of the heroes, along with four of the hosts, fell in battle. All that was left of the enemy was Cyclops, who had become Dark Phoenix. In the final showdown, Scarlet Witch and Hope Summers managed to defeat Cyclops and rid the world of the Phoenix Force.

3. West Coast Avengers

After the Grandmaster's death in the Contest of Champions, the cosmic gambler made a bet with Mistress Death to get his life back and manipulated the Avengers and the West Coast Avengers into fighting each other.

A showdown of epic proportions took place between Thor and Wonder Man, leading to Thor having to call upon the full power of Mjolnir to secure a victory. In a contest of martial arts, Captain America proved superior to Mockingbird, and Doctor Druid succeeded in putting Tigra in a trance. Moon Knight, Hank Pym, and Iron Man were able to take down Black Knight, Wasp, and Captain Marvel (Monica Rambeau.) Finally, in what was the most lop-sided matchup, Hawkeye had to attempt the impossible: defeat She-Hulk. After blasting her into the water, he waited for her to come up for air. When she emerged to take a deep breath, Hawkeye hit her with a gas arrow that rendered her unconscious. With the score 4-3, the West Coast Avengers won the contest.

Unfortunately, the entire game was revealed to be a ruse by the Grandmaster in order to take Mistress Death's power. Hawkeye once again had to use his ingenuity to trick Grandmaster and save them all.

2. Defenders

When the Enchantress turned the Black Knight to stone, the Defenders, joined by Hawkeye who had quit the Avengers, looked for a way to restore him to his natural state. Doctor Strange tried to communicate with Black Knight's spirit, but the Black Knight's message to Strange was intercepted and replaced by one from Dormannu and Loki. They told Strange that only the power of an artifact called the Evil Eye could save the Knight. This was Dormannu's way of gaining supreme power, but Loki turned on Dormannu, thinking that the Evil Eye would make Dormannu too powerful. So he convinced the Avengers to stop the Defenders from taking the Evil Eye. What followed was a storyline known as the "Avengers-Defenders War."

The Avengers and Defenders competed in one-on-one battles to obtain the scattered pieces of the Eye. Valkyrie, Hawkeye, Dr. Strange, and the Silver Surfer managed to defeat Swordsman, Iron Man, Black Panther, Mantis, Scarlet Witch, and the Vision. Unable to beat Namor, Captain America allowed Namor to take his piece. In the most explosive collision, Thor battled it out with Hulk for an entire hour until the Defenders and the Avengers discovered the deception, and interrupted the fight to take on Loki and Dormannu together.1. The Original Avengers

1. The Original Avengers

Avengers Captain America, Thor, Iron Man, Hawkeye, Black Panther, and Hulk.

After the Avengers took a trip through time using Doctor Doom's time machine, they returned to their own timeline to discover that the Scarlet Centurion (an alternate universe version of their time-travelling adversary, Kang the Conqueror) had drastically altered the past. They found themselves in a world where the original Avengers (Iron Man, Thor, Hulk, Giant-Man, and Wasp) had unknowingly done the Scarlet Centurion's bidding by killing all of the world's superheroes.

In an effort to stop them, the Avengers embarked on a mission to defeat their counterparts. Their biggest obstacle was the difference in power. The current Avengers lineup was without anyone who could come close to matching the might of Thor or Hulk.

After putting together a plan, Giant-Man and the Wasp managed to defeat their past selves, while Captain America took Thor out of the equation by keeping his hammer away from him for 60 seconds, causing him to revert back to the crippled doctor, Donald Blake. Hawkeye defeated Iron Man by destroying his armor with an acid arrow and hurried to help Black Panther with the Hulk. A sonic arrow turned him back into Bruce Banner.

With the evil Avengers defeated, the heroes were able to stop Kang and restore the timeline.