Not only is Falcon Captain America’s best friend (next to Bucky), he spent a spell wearing the red, white, and blue as Cap. But he actually got his powers working alongside Red Skull. Before he turned good he was a petty Harlem thug and Red Skull henchman, then on getting his powers quickly turned on Skull and teamed up with Cap. They’ve been bros ever since.
Rogue initially started out as an Avengers villain. She even took out Captain America! If you think about her powerset, it totally makes sense that she’d square off against Earth’s Mightiest Heroes. Still, she’s far more interesting as a tortured hero, which her decades with the X-Men have proven.
Gambit is one of those heroes that always seems to be up to something. That’s because he started as a villain, albeit a charming man-about-town thief of a villain. It was later revealed he was partially responsible for the massacre of the Morlocks. He’s made up for as a member of Xavier’s crew, though.
Deadpool started out as 100% villain. In fact, he’s jokingly based on a DC villain, Deathstroke (Slade Wilson/Wade Wilson, get it?). But he rapidly gained popularity, along with his own title, and a more flexible morality.
Hawkeye’s first encounter with the Avengers was.. robbing them. That’s right, one of the most iconic Avengers was a petty thief. They soon saw his talent and convinced him to join them. The Avengersindirectly nodded to his history by having Loki brainwash him into supervillainous shenanigans throughout most of the film.
Venom started as a villain specifically out to get Spider-Man. Eddie Brock knew all Spidey’s secrets, had all his abilities, and firmly believed that Peter Parker was responsible for everything that had gone wrong in his life. Eventually, he came to see that Spidey was just trying to make the world better, and he even fought alongside his former enemy. Nowadays venom is on Flash Thompson and is a full fledged government issued hero.
Black Widow often references her dark past, and she isn’t kidding around. Clair Voyant, the first Widow, was an anti-hero who killed evildoers and sends their souls to the devil. Natasha Romanoff, the current and more popular Widow, began as a Soviet spy and while she often played both sides, she also represented a very specifically Cold War image of nefarious, hyper-capable Russian femmes fatales.
In Vision’s very first appearance he was created by Ultron to be an enemy of the Avengers, a baddie designed to hate his “father” Hank Pym. But in his first arc, he realized he wanted to fight for good, and rebelled against his other father figure, Ultron.
It would only make sense that the son of Magneto would be a villain. Quicksilver began as a recurring nemesis to the X-Men. After years as a thorn in their side, he came around to light and started Avenging in earnest.
Scarlet Witch was still dabbling in villainy, even after she became an Avenger. It was mainly her love with Vision that brought he to the good side. Even then, she stripped almost every mutant on Earth of their powers, so she’s complicated.
She may help lead the X-Men now, but for years she helped lead another more nefarious group of mutants, the Hellfire Club. Forst was responsible for a whole lot of problems in the X-Men’s formative years, making her a fascinating choice to teach at Xavier’s School for Gifted Youngsters.
For a cat burglar, Catwoman does a fair amount of good in the Bat-verse. We blame Batman’s gruff charm. At one point, she was a more straightforward villain, but for a long time now she’s lived in a greyer area, a grey area in which she more often than not skews heroic.
Elektra began as Daredevil’s nemesis and sometimes lover. When she wasn’t dead, she would sometimes team up with DD. Nowadays she fights on the side of the angels. Sometimes. Elektra never quite settles on either side of the moral line.
One of DC’s major anti-heroes began as even less of a hero. In fact he began as afoe for Superman. While the over-the-top extraterrestrial bounty hunter has become more moral in many iterations, he has also remained villainous in plenty of others.
This is an entire team of villains turned heroes. As led by Baron Zemo, the Thunderbolts were originally a team of villains who disguised themselves as heroes for their own evil ends. Then, over time, they became actual heroes. Even superpeople can fake it ’till they make it.
Plastic Man began as a low-level crook. He was an orphan who quickly fell into a life of crime. He lived as a thief for a short time after gaining his powers, but quickly realized he should use his elasticity for the benefit of all mankind. For a time he was a double agent, using his connections to the underworld to catch bad guys as his alter ego.
Morbius, the Living Vampire
Morbius is a vampire. That in itself puts him at a slight disadvantage in the heroism department. He began as most vampires do, feeding on people. But then he began to specify only bad folks, then was able to synthesize a serum and lay off the human consumption altogether, so from there, it was only a short jump to using his powers for good.
Nowadays Prowler is Spidey’s sidekick and occasional stand-in in the Marvel Universe, allowing Spider-Man to be seen alongside Peter Parker and throw people off the trail. But he started as a burglar using his tech knowledge to steal whatever he could. He was one of Spidey’s foes for years before ultimately straightening himself out.
She’s a tricky one to pin down. She began as a member of the Teen Titans, and then in issue #40, she was revealed as a traitor. After being kicked off the team, she reformed and often teams up with Batgirl. So she’s a villain disguised as a hero who turned into a real hero.
Shade began as a multi-generational villain. He fought against Flash in both the GOlden and Silver ages. He eventually evolved into a mentor for Starman and more of a morally ambiguous anti-hero than full-on bad guy.
He first appeared as a member of the League of Super Assassins, but it was promptly revealed he was being controlled by Dark Man to attack the Legion of Superheroes. After breaking free of Dark Man, Blok slowly joined the Legion of Superheroes.
Not only is Pied Piper a reformed supervillain (since Barry Allen’s death Hartley has been on the up and up) he’s also one of DC’s first openly gay characters. He used to be one of Flash’s consistent bad guys, but now he’s more of a robin hood type figure.