In The DCUCrisis CrossoverUnderworld Unleashed lots of villains (and a few Anti Heroes) sell their souls to the demon Neron in exchange for additional powers. (Well, most of them. Lex Luthor did it to cure his cancer. The Joker did it for a box of Cuban cigars.) Many find that the gifts have nasty side effects. The demon's ultimate plan was to corrupt, and then buy, the soul of Captain Marvel. When Cap selflessly offers his uncorrupted soul in exchange for nothing but the safety of his friends, Neron has no choice but to accept the deal, even though Captain Marvel had offered exactly what Trickster had told him, and so was safe: Neron could not collect if there was nothing in the bargain for the other person.
In a later story, Kid Red Devil, a former C-List sidekick, is offered super powers by Neron so that he can join the Teen Titans. He is allowed to keep his soul as long as his trust in his hero, Blue Devil, isn't broken, otherwise he loses his soul to Neron when he turns twenty. Naturally, things don't work out; in a Call-Back to Underworld Unleashed Neron immediately tells him that his aunt's death was the result of the deal between Neron and Blue Devil (in Blue Devil's defence, the deal was just to destroy a minor unmanned power station, but despite him making sure that nobody was on duty and a relay station would kick in to carry the load, the station's destruction contributed to an electrical outage that caused the death of Red Devil's aunt).
Later, the Trickster himself offers Neron a bargain to protect his ex-girlfriend's son and the rest of the Rogues Gallery. He asked for nothing for himself, for the same protection. Fortunately, he only later did the arithmetic for the son's age.
Another interesting story with Neron involved, weirdly enough, Santa Claus. After he'd captured the entire JLA, Santa defeated Neron by giving him a Christmas present with no strings attached and asking for nothing in return, which violated his every rule of trade and contracts. This was just a bedtime story told by Plastic Man...
Another one had Neron approach Oracle with a deal - the restoration of her legs to be his historian. No soul-selling required, just record what was going to happen. She actually thought about it for awhile, but turned it down in the end, stating that if she did take it, she'd still be selling her soul either way. Neron quietly dropped the subject and left peacefully.
When Neron brought the Flash's Rogues Gallery back wrong, Wally and his wife Linda made separate deals with Neron to set them right (since they were mindless killing machines far more evil and dangerous than the real Rogues were). Except instead of their souls, Neron asked each to give up their love for the other. Both agreed, and they split. (Un)fortunately, holding their love 'polluted' Neron, who began to treat the damned with kindness. He asked them to take back the bargain, and both refused (since neither one cared about the other, neither had any desire to get their love back). Ultimately Neron begged them to take a new deal, taking back their love in return for him releasing any and all remaining hold on the Rogues.
Subverted in an early story arc of James Robinson's Starman for DC where a demonic poster stole the souls of whoever looked at it. The demon offered to return the souls of all he had taken if Starman, the Shade and Matt O'Dare gave up theirs. They agreed and the people were freed but they kept their souls because the demon stated that part of the rules in such bargains was that he couldn't keep a soul offered in a purely selfless act.
Invoked in Crimson Mist, the third novel of the Batman Vampire trilogy, when Gordon and Alfred observe the vampire Batman ascending from the roof of the GCPD in a reddish mist after they bring him back and explain Gotham's current crime wave, both men musing that it's as though their plea for help has been sealed in blood as they turn the demonic Batman on Gotham's more conventional criminals.
Defied in the classic story Superman #149: Death of Superman. On trial in the bottle city of Kandor for Superman's murder, Luthor smugly thinks he'll get out of this. After being found guilty, Luthor offers to restore the Kandorians to their full size in exchange for his freedom, certain they'll take the deal. To his shock, the Kandorians would rather stay in the bottle than owe their freedom to Superman's killer and send Luthor to the Phantom Zone.
During a late 90s arc, Lex Luthor bought out the Daily Planet for the express purpose of shutting it down. Later, Perry White found backers to help him buy the Planet back, rehiring Clark, Lois, Jimmy and the rest of his staff to put out the paper... Only for Lex to sell it to Perry for the price of one dollar. It was later revealed that Lois had secretly brokered a deal with Lex for the sale of the Planet; in exchange, Lois agreed to kill a story of Lex's choice at an unspecified date in the future. It turned out to be a story that would've sunk Lex's presidential campaign. Lois gets out of it by telling Clark, who writes the story himself (after all, he didn't make a deal with Lex).
After Lex Luthor accidentally releases a demon from Hell named Saturn on Earth, the demon offers him a bargain... except it turns out it was really Superman in disguise, tricking Luthor into revealing where the Hell portal was located.
Saturn tries to get Superman to break his no-killing vow (to morally break him down) by possessing an innocent girl, then telling the hero the only way to stop him from further ruining the World would be to kill her. However, Superman refuses, even if it means the two would be locked in eternal combat. It turns out that by refusing, Superman actually won a wish from the demon (the rules governing demons demanded it) and Superman uses it to return everything to normal.
In Two for the Death of One, Syrene wins her duel with Satanis by casting him into Hell. Satanis got out of there by agreeing to becoming one agent of the Devil himself.
In what may well be his greatest moment, when John Constantine discovered he had terminal cancer, he sold his soul to Lucifer for a cure. Naturally, Lucifer reneged and showed up as John was dying, gloating on all the tortures he would give him. Suddenly, in come the other two Lords of Hell, Satan and Beelzebub to show up and relate that John sold his soul to each of them as well. They argue before John points out the issue: All three of them have a claim to his soul and would have to go into a war so vicious that God himself would have to step in to wipe out all three. The only way to get out of this jam? Cure John of his cancer and call the deals off. Nothing says Magnificent Bastard like this.
In Batman 666, Future Bad Ass Damian Wayne, having taken the mantle of Batman, made a deal with the Devil to protect Gotham. Even when pumped full of bullets, he survived and his injuries healed almost immediately afterwards with no lasting effects.
Wonder Woman (1942): Helen Alexandros made a deal with Ares to become the first Silver Swan. She regained her talent as a ballet dancer and was made to appear beautiful instead of homely; in exchange Ares would use her as a weapon against Wonder Woman. When Ares was done with her he removed the power he had bestowed on her, returning her to her mousey handicapped former self.
Wonder Woman (1987): The White Magician made a deal for more Dark Magic power to be able to defeat Wonder Woman, but when he tried to fully use his new power it ended up killing him as soon as he'd killed the current Wonder Woman (Artemis).
Wonder Woman (2006): An even more evil and vindictive Ares than usual, possibly due to the deaths of his children, warns a traitorous Amazon that those who make deals with him rarely get what they want from said deals. This does nothing to dissuade her.
DC's Hi Hi Puffy AmiYumi #2 had "Dark Agent." The girls get rid of Kaz and sign a contract to make the Devil their agent, for which in return they will get success and riches beyond their dreams. But they become bored with it after awhile, and they can't renege because the contract was for all eternity. Kaz arrives and challenges the Devil to a duel with guitars to win back the girls.
The Sandman (1989): During the Seasons of Mist arc, Lucifer discusses this with Dream. He has no idea where mortals got the idea of him making deals with them, and considers it a feeble attempt to avoid responsibility for their actions. What would he do with a soul, even if he could "own" one, anyway?
Swamp Thing: During Alan Moore's run, Jason Blood reveals he made an agreement with Etrigan some time before to try and moderate the demon's appearance. However, as Jason points out, there was a little flaw in this plan: Demons cheat, it's in their nature, and the deal is having a negative impact on Jason. Meanwhile, as this is happening, Matt Cable is in a car crash, and makes a deal with another figure in exchange for what he thinks is his life... It's Anton Arcane, Creepy Uncle of his estranged wife Abby, and Matt's corpse is possessed.
In Zatanna: Everyday Magic, Nimue Revensong tried to offer Constantine as an Human Sacrifice to a group of demons known as "The Traders", in exchange for a magic needle that could absorb the life force and magic out of whomever it pierces.
In Zatanna (2010), villain Brother Night sacrificed the souls of thirteen children to the lords of Hell atop Mount Diablo in return for his power as an Evil Sorcerer and Necromancer. When Zatanna faces him atop Mount Diablo to save her friends, she defeats him by using her Sdrawkcab Speech to force him to renounce his power and his contract, freeing the souls of the kids to move on to their proper afterlife and depowering him so that he can be incarcerated by the regular authorities, but also dooming him to Hell when he dies.
In Hawkgirl (2023), this is Vulpecula's MO: find someone with a bad life, travel back in time, and offer them whatever they want most in the world, as long as they always wear a fox-shaped pendent of Nth metal. Then travel back to the present, when their body is now infused with Nth metal, and attempt to use this power to build a portal to the Nth world. This has the useful side effect of turning them into monsters based on their wish, under her control.
