The DC Comics Universe is very vast and over the years, almost every supervillain has had an opportunity to turn to the good side. While some of them have made the switch, the most difficult part is to keep at it because it's very easy for a character to revert back to their old ways.
Many DC supervillains have tried and succeeded in their attempt to redeem themselves, with Red Hood and Plastic Man being the pick of the bunch. Taking that as an inspiration, one would like to think that joining the side of the good guys wouldn't be that tough. Still, there are a couple of guys who blew their opportunities to become a superhero.
10 Clayface
Basil Karlo had a very rough beginning to his dream. He wanted to be an actor but when he knew he wouldn't be able to cut it, he went to Penguin for help. As a result, Clayface was born, having to do the dirty deeds for a classic Batman supervillain in return for his acting career.
At first, he didn't like the petty thefts and he had enough reason to get out of the business. But after a while, Karlo developed the ability to copy one's DNA and power consumed him. He could have easily given up all of it for his dream but instead, he chose violence.
9 Captain Cold
Captain Cold has always been on the side of the baddies, although the New 52 allowed him to change his ways. During a storyline when the Justice League was corrupted, Lex Luthor, Black Adam, and Captain Cold came to the world's rescue.
They formed the Injustice League and fought the Crime Syndicate while taking care of the superheroes they swore to fight. Captain Cold was hailed as a hero after this but that didn't last long as his hatred for The Flash pushed him towards evil.
8 The Joker
The Joker once became good or he gave away the impression that he has resorted to the good side. In the White Knight storyline, Joker was seemingly cured of his illness and he became a superhero. He went by the name of Jack Napier and his only motto was to remove the power the Bat-Family had over Gotham.
Despite making it look like he wanted the law to be bigger than anyone else, it turned out that The Joker had bad intentions on his mind. He totally convinced everyone he became good but that's not how the Joker works, is it?
7 Harvey Dent
Harvey Dent is an iconic presence in Gotham. Be it his burned face or notorious actions, there is something about him that screams he will never become good. But a storyline saw that happen as Two-Face was relieved of his persona and allowed to be good again.
The Harvey Dent Gotham knew was never coming back, though, as he used his position to employ unlawful methods. He was never going to be a superhero. The best he can do is be an anti-hero but even that doesn't seem to be happening anytime soon.
6 Catwoman
Catwoman has flirted with the good side of Gotham for a while now, owing to her attraction towards Batman. One of the most fascinating things about her character is the fact that she is a street smart thief and yet, Bruce Wayne is attracted to her.
At one point, Catwoman and Batman were all set to get married, which would've halted all of Catwoman's bad activities. But unfortunately, the wedding was called off and she resorted to her old ways.
5 Deathstroke
Deathstroke is a mercenary and one of the best Teen Titans supervillains of all time. His name resonates with the DC Universe unlike any and even someone as evil as him has had the opportunity to be good. He has not only joined the Teen Titans but he has also led his very own superhero group in order to convince the world that he has changed.
Unfortunately, Deathstroke has always gone back to his murderous ways, showing how difficult it is to do what the superheroes do.
4 Poison Ivy
Another one of those morally flexible characters, Poison Ivy thinks she is fighting the right fight but the problem is, she is just doing it the wrong way. She just wants to keep the plants safe but she is willing to sacrifice human lives when it comes down to it.
She has gone as far as to feed humans to plants. Despite that, she once joined the Birds of Prey and she has also worked with Batman. But unfortunately, those stints with heroes haven't lasted and she has given into her villainous nature.
3 The Riddler
Edward Nigma, aka The Riddler, is another incredibly well-known Batman supervillain. He has the brains of a genius and has often tricked the Dark Knight. But what fans probably don't know about him is the fact that he once helped authorities catch the most distinguished criminals.
He didn't have any good intentions behind it, instead, he just wanted to know what mistakes criminals make, so that he could come up with the perfect crime. In those moments, he could've given up his villainous ways and become a detective but his hate for Batman was too much to give away.
2 Black Adam
Black Adam has trodden a fine line between being a supervillain or a superhero. In fact, on multiple occasions, he has acted as a hero but the worst thing about him is his selfish motives behind every act.
Much like Captain Cold, Black Adam was also hailed as a savior after fighting the Crime Syndicate. But unlike Lex Luthor, he didn't think of joining the Justice League, instead, he decided to continue on his morally ambiguous way.
1 Lex Luthor
Lex Luthor became a full-fledged superhero in the New 52 but that wasn't the only time he had an opportunity to follow Superman's mentality. In fact, in his original run, he made loads of charitable donations while fighting the alien threat looming large on the planet.
So much so that he once became the President of the United States. Unfortunately, he couldn't stay good for long and his presidency days came to an end due to his undying hatred for the Man of Steel.