One of the biggest problems with superhero comics is that sometimes things get a little stale. There's only so many times a hero can best the same villains before readers grow tired of the whole thing. There's always giving the mantle to a new or old character, but that runs the risk of alienating readers. However, turning that hero into a villain can open things up and provide some compelling stories.
DC Comics has done this memorably many times. Some times it worked, other times it didn't. This list is going to run down the very best times a hero broke bad.
10 Niles "Chief" Caulder
Niles Caulder was a genius paraplegic who used his vast intellect to create many inventions and innovations that made him wealthy. He would bring together the Doom Patrol, helping each member with his inventions and acting as the brains of the group.
Towards the end of Grant Morrison's run, it was revealed that the Chief was responsible for the accidents that made the Doom Patrol into "freaks" and that he had built a nanotechnology bomb that would destroy half the world and transform the survivors into "freaks of nature." The team and readers alike were shocked by this turn of events.
9 Maxwell Lord
Maxwell Lord was the financier behind the Justice League International. He was a stereotypical '80s businessman and mostly played for laughs. During the Invasion crossover, he was given mind control powers and would die of a brain tumor, only to be resurrected in a cyborg body.
In 2005's Countdown to Infinite Crisis, it would be revealed that there was much more to Lord than meets the eye — he was the Black King of Checkmate, had taken over Batman's Brother Eye satellite, and was working against the heroes. Lord would even shoot his friend, Blue Beetle, in the head. Even though the continuity has been changed several times since, Max has remained a villain.
8 Atom Smasher
Albert Rothstein was the godson of the Atom, the Golden Age hero, and was also the grandson of the villain of Cyclotron. Albert's powers of super strength and size manipulation made him a formidable opponent and he would eventually join the Justice Society of America.
He would butt heads with reformed villain Black Adam before the two gained an understanding of each other and became friends. When Adam left the team to take back his home country of Khandaq, Atom Smasher would accompany him, bringing him to blows with his former team members.
7 Hawk (Hank Hall)
Hank Hall was one half of the superhero duo Hawk and Dove, first with his brother Don as Dove, then his girlfriend Dawn. He had a fiery temper and was empowered by the Lords of Chaos with super strength and durability.
It was revealed in Armageddon 2001 that Hank would become the world conquering supervillain Monarch, putting him on par with Superman and Wonder Woman. After becoming Monarch in the present day, Hank would go on to become the time-altering villain Extant, before dying and being resurrected at the end of Blackest Night as Hawk.
6 Jericho
Jericho was the son of Deathstroke the Terminator. Left mute after an attack by his father's enemies, Joe Wilson would gain the ability to possess others. After his father took out the Teen Titans, Jericho would help Nightwing rescue his teammates and would go on to the join the team.
During his time with the team, Jericho would be possessed himself by the corrupted souls of Azarath and become evil. He would fight his friends with the help of the Wildebeest Society before being able to take back control of his body and beg his father to kill him. Deathstroke would oblige, ending the threat of his possessed son.
5 Terra
Terra was another member of the Teen Titans who went bad. Sister to the hero Geo-Force, Terra had the ability to control dirt and stone. She had an abrasive personality, but seemed to soften the more time she was with the team, even appearing to start a relationship with Beast Boy.
It was all a ruse, though. Terra was working with Deathstroke to take down the team and would betray her "friends." However, she began to feel used by Deathstroke and lashed out, using her powers to try and not only kill her former teammates, but Deathstroke as well. However, her anger got the best of her and she would lose control, taking her own life.
4 Jason Todd
Jason Todd was a orphaned street kid who stole the wheels off the Batmobile. Batman would take him in, making Jason the second Robin. He was more hot-headed than his predecessor and struggled with his temper. Eventually, he would be lured away by the return of his mother, and Joker would kill him.
Years later, a new Red Hood would surface in Gotham. He would take control and go after Black Mask's criminal empire. It would be revealed that this Red Hood was none other than Jason Todd returned from the dead. Todd would eventually rejoin the Bat-family as a hero.
3 Superboy Prime
Superboy Prime was the Clark Kent of Earth Prime, an alternate Earth where he was the only person with superpowers. Prime was drawn into the Crisis and helped Alexander Luthor and the Superman of Earth 2 defeat the Anti-Monitor. As the multiverse was replaced by something new, the three of them, along with Earth 2's Lois Lane, would go to a paradise dimension.
However, paradise wasn't all it was cracked up to be for Luthor or Prime and the two would begin to visit the DCU proper and meddle with things. They would try to bring the multiverse back but fail. Luthor would be killed by Lex Luthor and the Joker, but Superboy Prime would go on to be a threat to the universe, battling the likes of the Green Lantern Corps, Superman, and the Legion Of Superheroes.
2 Wally West (Post-Rebirth)
Wally West returned to the DC Universe in DC Rebirth #1 and fans and heroes alike were happy. He would become a symbol of hope and join his friends in the Titans. However, he would still remember the old universe, his old life with his wife Linda and their kinds Jai and Irey, and it would slowly drive him crazy.
He would go to Sanctuary, a place for superheroes to get mental help and would lose control, accidentally killing everyone there, including his friend Roy Harper. He would spare Booster Gold and Harley Quinn so they could be blamed for the murders and escape to the future, where he would kill his future self to leave the body behind at the scene and end his pain forever. Booster and Quinn, with the help of Batgirl, would stop Wally and he would become imprisoned.
1 Hal Jordan
Hal Jordan is one of the greatest heroes of the DC Universe. As a member of the Green Lantern Corps, he has saved the universe time and again, both on his own and as a member of the Justice League. Armed with a power ring that can do nearly anything he can think of, Jordan was a shining example of the heroic ideal.
Until the Cyborg Superman destroyed his home town, Coast City. Mad with grief, Jordan would try to gain enough power to resurrect the city, killing the entire Green Lantern Corps before being stopped by new Green Lantern, Kyle Rayner. Jordan wasn't done, though, and would return as the villain Parallax, trying to reboot the multiverse. He would be defeated again, but would eventually redeem himself, as it was revealed that he was possessed by the fear entity who's name he had taken as his own — Parallax.