Being a hero is not easy, especially in the Marvel universe. When they're not going up against villains trying to take over or destroy the universe, they're often having to stop one of their own. Throughout the universe, heroes have turned to the dark side for various reasons.
Whether possessed by an unknown entity, wronged by another hero or simply tired of having to be the better person, there are plenty of reasons a hero can turn evil. Some manage to find their way back to the light, while others embrace their inner villain. Either way, the heroes better be ready to fight them.
Update October 25, 2022, by Sarah Prado: With new stories always being developed and ever-changing circumstances, there are some heroes that might take a dark turn. Fans have seen that heroes can turn on each other should they have a disagreement. Some turn evil for other reasons like having a dark side in them that they have to contain. Then there are others who are evil in other storylines. Either way, these heroes have either dipped their toes into villainy or gone full evil, which shows them in a new and frightening light.
14 Colossus
Though he's mostly been on the side of good, Colossus has found himself opposing his allies on more than one occasion. After being brainwashed by Arcade, he fought his fellow X-Men until they were able to counter Arcade's doings.
After his family died, Colossus joined the Brotherhood of Mutants. Luckily for his allies (and unfortunately for his enemies), Colossus always seems to make his way back to the side of good and usually stays there.
13 Adam Warlock
Adam is a hero that has a dark side to him known as Magus. Magus is actually a future version of Adam who went insane due to using the Soul Gem. Though Adam tries to maintain his good self and is horrified by what Magus has done in the future, he is constantly going back and forth between good and evil.
He’s fought and defeated Magus plenty of times, but Magus will always come back in some way. So long as Adam is alive, Magus will always be a part of him as his dark and evil side. The most Adam can do is try his best to suppress it.
12 Hank Pym
In the Marvel Cinematic Universe, Hank Pym is a good guy and a previous user of the Ant-Man suit. However, this hero has a dark history outside the MCU and some of it is controversial. Hank and his wife Janet fought in the Avengers as heroes and were married for a while. Sadly, Hank had a mental breakdown after he was suspended. After this, he planned on setting a robot loose to attack the Avengers and “save” them from it.
When Janet found out, she tried to convince him not to, but he struck her away. While Hank does eventually return to being a hero, it’s still frightening to see how dark he can be. The Ultimate Marvel comics showed a more abusive side to him in which he had his ants attack Janet when she was shrunken down to Wasp size. Plus, Marvel’s What if…? series shows that Hank could be one of the deadliest villains as he killed all of the Avengers before they could even team up.
11 Madelyne Pryor
Created as a clone of Jean Grey and sent in Cyclops' direction after Grey’s death, Madelyne seemed doomed from the start. She and Cyclops had a whirlwind romance and married rather quickly. She had Jean’s powers and then gained Asgardian magic for a short time, during which she healed the old wounds of the X-Men and anyone else around her.
Unfortunately for Madelyne, word reaches Cyclops that Jean is alive, and he abandons Madelyne and their son Nathan. Madelyne and Nathan are attacked by Marauders, and Nathan is kidnapped. Her son's fate and Cyclops’ abandonment put Madelyne on a dark path, and she has consistently remained a villain since.
10 Angel, AKA Archangel
One of the earliest members of the X-Men that fell from grace, Warren Worthington III started as the hero Angel for the X-Men and used his wings to fly and save people. However, his wings are mutilated during the Mutant Massacre and then amputated against his wishes by Cameron Hodge, who personally hates him. Angel eventually joins Apocalypse and his wings are restored after agreeing to serve him.
He does turn back to being a hero, but Angel continues to go back and forth between that and villainy. There are times when the Archangel persona wants to come out and succeeds due to Warren’s confusion. However, it seems the Angel part wins a little more than half the time once Warren finally gets himself together.
9 Bucky Barnes, AKA The Winter Soldier
Like his MCU counterpart, the Bucky Barnes in the comics was turned into an assassin after he seemingly died on a mission with Captain America. In reality, he was captured and brainwashed. When Bucky returned as the Winter Soldier, he was one of the deadliest villains, being able to go head-to-head with his best friend.
Despite his tenure as a bad guy, he’s on the side of good now. Yet, Bucky's time as a villain was dark enough that it still haunts him to this day and he remains one of the more prominent examples of a Marvel hero becoming a villain, if only for a short while.
8 The Hulk
The Hulk is one of the strongest heroes in Marvel, but his rage puts even his allies on edge. After being deemed too dangerous by the Illuminati, the Hulk was banished to a different planet, where he built a new life for himself. Unfortunately, an explosion kills his wife, and he blames the Illuminati.
The Hulk comes back to Earth with a vengeance, defeating most of the X-Men and Avengers along with other strong heroes. His time as an antagonist proves that the only thing deadlier than a rampaging Hulk is a vengeful Hulk.
7 Black Widow
Black Widow has always walked the fine line between good and evil, but she’s done some awful things that seem to come naturally to her. In the Ultimates universe, Black Widow is possibly the worst person in the series. She seduced Tony Stark, conned him into an engagement, and killed Jarvis. She murdered Hawkeye’s family, and to top it off, framed Captain America for it.
Even outside of the Ultimates universe, she’s not exactly the most heroic. She’s killed her best friend Marina after being tasked to do so, and even killed Marina’s cat to make sure there were no witnesses. When she's on the side of good, her morals are still ambiguous.
6 Reed Richards, AKA The Maker
This version of Reed Richards started very much the same as the original one. Unfortunately, after most of the heroes died and Sue Storm (his love) rejected his proposal, Reed Richards snapped. He started working with aliens and his view of the world changed.
Reed murdered his parents and faked his death, joining the aliens he dealt with. He sought to end humanity because he believed they were an inferior species. With his incredible comic book intellect, he had the potential to be one of the deadliest villains in Marvel history.
5 Jean Grey
Jean Grey is among the first Marvel characters to come to mind when discussing heroes turned villains. Jean has fought alongside the X-Men for a long time and is one of their most prominent members and most powerful mutants in the world.
When she emerged as Phoenix, Jean’s powers were beyond anything the world had ever seen. This made her a prime target for the Hellfire Club, which messed with her mind and brainwashed her. As Dark Phoenix, Jean commits mass genocide, making her a bigger threat than Galactus. Her power is so great that she can barely control it, making her extremely dangerous.
4 Daredevil
Daredevil is one of those heroes that believe villains can be reformed. One just needs to watch the Daredevil scene in episode three of season two in which he and the Punisher argue over how they treat criminals. He truly believes that everyone deserves a second chance and that redemption can be reached.
However, in the Heroes Reborn storyline, Daredevil becomes a religious zealot who goes around beating criminals to death and is known as the Saint. It’s very unnerving to see a man who once believed in the best in people now using his position as a cleric in a church to find targets. He listens to criminals confess their sins to him and targets them later on.
3 Cyclops
The only thing more shocking than Jean Grey's villainy is seeing Cyclops turn against his allies. For many years, Cyclops was one of the leaders of the X-Men and a role model for younger mutants. He serves as a foil to Wolverine as they fight together as allies.
Tragically, Cyclops becomes possessed by the Phoenix Force and kills Professor X, shocking everyone. After being stopped, Cyclops admits that he would do it all over again, as he wanted to build a new world where mutants would thrive and not have to hide. Yet, he does regret killing Professor X.
2 Alex Wilder
Alex comes off as an aloof teenage boy but seemed to care for the Runaways. He was the one who organized their escape after finding that his and the other Runaways’ parents were actually villains. Alex was the de facto leader of the group and worked with them to find out who their parents were working for. It wasn’t until the final fight with their parents that Alex betrayed the Runaways and revealed his true intentions.
He tells the group that he’d been using them for his own gain, intending for him and his parents to live in the new paradise after the world is destroyed. Alex was killed by the Gibborim after his plan failed and he insulted them. Alex was eventually resurrected and has been causing havoc since.
1 Captain America
It was a shocking and dark day for Marvel fans to see Captain America, the poster boy of all things good in superheroes, utter the words “Hail Hydra.” For a long time, Captain America was the most squeaky-clean hero in Marvel. He was the boy scout of the Avengers, always doing right by others while maintaining his own morals and thoughts. Captain America was a simple man, just trying to save and protect the world.
Marvel decided to throw fans in for a loop during the Secret Empire storyline. It turned out that Steve was controlled by the Hydra Supreme, making him an agent for Hydra. By the end of the story, Captain America points out that no one should blindly trust one another — not even superheroes.