Being a hero's best friend doesn't automatically mean being a good person. Despite being close, heroes and their best friends can have disagreements and even fundamental differences that can't ever be resolved. Sometimes the greatest friendships have the biggest potential for betrayal and drama.

RELATED: The MCU's Greatest Friendships, Ranked

The Marvel Universe is full of heroes and villains who break promises and leave friendships behind them. Comrades turned foes, lovers turned enemies, and family bonds broken, there are several examples of friends turned enemies (and sometimes friends again) in the Marvel Universe.

10 Deadpool And Taskmaster Are Rivals And Allies... For the Right Price

Deadpool and Taskmaster in the Comics

Taskmaster isn't an outright villain; he's just willing to kill for the highest bidder. From contract killer to trainer to lead henchman, Taskmaster has done it all. Taskmaster and Deadpool often team up and work well together, but the biggest problem their friendship faces is the job they share: merc work.

Although the two have teamed up in the past, when the money is right, they'll fight for the right to a contract. As a result, they'll be at each other's throats during one mission and teaming up for a heist the next time they meet. It's all in a day's work – and hefty payouts – for these mercenaries.

9 Miles Morales' First Villain Was His Beloved Uncle

Miles Morales and Aaron Davis

Miles Morales is one of the best 21st-century additions to the Marvel Universe. As a result, an entire generation of fans have grown to love him and enjoy his exploits as Spider-Man. Miles' story is inextricably linked to his uncle Aaron Davis, who isn't only responsible for his powers but is also one of his closest family members.

It was Aaron who stole the spider that bit Miles, and he also became Miles' first iconic villain. Miles has great parents as role models, but his Uncle Aaron was someone he turned to when he felt like he couldn't talk to his parents. Having an outside mentor is a hero's rite of passage, and losing Aaron as his was a huge moment in Miles' character development.

8 Elektra And Daredevil Have Been Friends, Lovers, And Enemies Multiple Times

Daredevil bandages Elektra in What If? comics

Elektra Natchios and Matt Murdock have a long and fraught history. They met at Columbia college and were both trained by the same master, Stick. However, Elektra's training with The Hand is where the two diverge. She became an assassin for hire and Matt was determined to fight for the people of New York, which included challenging threats like The Hand.

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Elektra didn't stay loyal to the Hand after they betrayed her, and she eventually vacillated between fighting them and being a part of their ranks. As Elektra's loyalties fluctuated, so did her relationship with Matt. She's recently taken on the Daredevil mantle while Matt's been imprisoned in Daredevil: Woman Without Fear by Chip Zdarsky. So, although they're friendly now, the chances are they'll be at odds again in the future.

7 Trick Shot And Hawkeye Went From Family To Foes

Trickshot confronting Hawkeye, classic costume Hawkeye pointing bow, and Swordsman pointing his sword split featured

Barney Barton is Clint's relatively unknown older brother. Their abusive father was killed in a car crash, along with their mother, and they were shuttled from foster home to foster home until they ran away with the circus and fell into the clutches of Swordsman. Barney and Clint started off as criminals until they both reformed, with Clint becoming an Avenger and Barney becoming an FBI agent.

Barney was eventually turned against Clint by Baron Zemo, going from a loving brother to a regular foe. Clint isn't often focused on in the Marvel Universe, but the fact he worked hard to reform himself and still tries to reach out to his brother are among the reasons he's one of the best characters they have.

6 Yelena Belova Has Tried Reform, But She Still Ends Up Fighting Natasha

Yelena Belova and Natasha hold guns to each other's heads in Marvel Comics

Natasha Romanoff is the definitive Black Widow, but she isn't the only one. The other most famous graduate, Yelena Belova, is also a formidable spy, and she and Nat are often at each other's throats. In fact, Yelena's first mission was to kill Natasha, but Natasha took the opportunity to try and help her see the truth. She also convinced her to strike out on her own, away from The Red Room.

Belova started her own business and made a life for herself. However, her time away from the world of espionage and superpowered people didn't last. She ended up being hired by the likes of Norman Osborn or manipulated by various forces such as AIM, and though Natasha tries to help her, they still find themselves at odds more often than not.

5 Xavier And Magneto Are One Of The Most Iconic Friends Turned Enemies Duo

Charles Xavier and Magneto

The philosophical argument between Xavier and Magneto is perhaps the greatest one in comics, causing two people who believe in defending their people into mortal enemies. Their battles, machinations, and manipulations have defined the struggle of the mutant race for decades.

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In recent times, these former friends turned enemies have become friends again – or at least uneasy allies. For example, Magneto has been an instructor at Xavier's School and an X-Men member for several missions. Furthermore, with the development of the Age of Krakoa – an era where the X-Men and mutants have their own homeland – the two are allies trying to ensure Krakoa's health and status.

4 Reed Richards And Doctor Doom Are The First Friends Turned Enemies Of The Marvel Age

Reed Richards and Doctor Doom face off in Marvel Comics.

The Fantastic Four are the First Family of Marvel Comics. Their book launched the Marvel Age of Comics, and a lot of characters first appeared on their pages. One of the most iconic villains to come from The Fantastic Four is Reed Richards' college roommate, Doctor Victor Von Doom

Doctor Doom is a dangerous genius, magician, scientist, inventor, and dictator all rolled into one. His clashes with Reed include impressive feats such as absorbing Galactus' Power Cosmic and reconsolidating the Marvel multiverse into Battleworld in Secret Wars. Doom will never reconcile with Richards, but their rivalry is so epic it'd be hard to see them as allies anyway.

3 Bucky's Shock Return Shook Captain America (And The Fans)

Captain America vs Winter Soldier in Marvel Comics

Ed Brubaker's Winter Soldier comic arc was the most explosive Captain America story in a long time. The shock revelation that Bucky Barnes, who was Cap's best friend in his early days, also survived was a great twist. It also made his brainwashing as a super-soldier assassin all the more tragic. The battle for Bucky's soul was a compelling one, and his redemption journey and heroic status were some of the most popular Marvel stories in the 2000s.

While Cap and Bucky rarely find themselves on opposing sides, their initial story was a powerful one. The harsh reality of Cap's past coming back to haunt him is something comic fans still talk about, which is why it was adapted for one of the most beloved MCU films.

2 Peter Parker Lost His Best Friend, Harry Osborn, To The Goblin Legacy

Peter Parker looking at Harry Osborn passed out in his bed after taking drugs in Marvel Comics

Harry Osborn's fall from grace is a particularly sad story. His girlfriend, Mary Jane Watson, leaves him while he's dealing with an amphetamine addiction, and he overdoses shortly after. After Norman sees his son in the hospital, his Green Goblin persona returns. He kidnaps Gwen Stacy to antagonize Spider-Man and throws her off a bridge, leading to Spider-Man's infamous dive and her death by whiplash. In a rage, Spider-Man confronts the Green Goblin and engages in a violent altercation that results in Norman accidentally impaling himself on his own glider.

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The tragedy becomes too much for Harry to bear, leading to his own break and transformation into the second Green Goblin. The entire saga and fall of the Osborns, as well as Gwen's death, mark a painful period in Peter's history. Although there wasn't an out-and-out betrayal, the mental health issues, misplaced anger, and untimely deaths are some of the heaviest and character-defining Spider-Man stories.

1 Namor Has No Friends, Only Future Nemeses

Herb Trimpe's rendition of Namor and Hulk grappling underwater

Namor is arguably the biggest jerk in comics. Arrogant, pompous, and unlikable, Namor's birthright as King of Atlantis gave his claims some credence. His mutant physique that makes him a powerhouse – even more so when he's in water – also helps. Namor has teamed up with and also turned on the likes of The Hulk, Doctor Doom, the Defenders, and the X-Men.

That isn't to say Namor doesn't have friends. He was a founding member of both the Invaders and the Defenders, and was even an Avenger for a while. The problem is, Namor's friendships come and go on a whim. He can, and has, turned on just about everyone who's stood beside him. With friends like these, who needs a rogues' gallery?

Next: 9 DC Heroes Whose Nemesis Is Their Best Friend