In Aquaman (1991), Aquaman was already wrestling with self-doubt and hatred when Thanatos came in to try and finish the job—but making Aquaman confront his fears directly helped him accept and move past them.
In the first story arc of Neil Gaiman's The Sandman, failed supervillain Doctor Destiny gets hold of the amulet containing the title character's power, and during the climactic battle (which he was winning anyway) he decides to destroy it, figuring that will leave Morpheus powerless and easy to defeat. Instead, destroying the amulet merely releases the power, which flows back into Morpheus, making him more powerful than he was before...
In one of the spinoffs, it's revealed that the first Despair convinced a sun-god to create life on an unstable planet, knowing that the planet would be destroyed eventually and leave a single survivor who would have to live his life in despair. The sun was Rao, the planet was Krypton, and the survivor was Kal-El, a man not known for giving into despair.
Forever Evil (2013): By moving the moon out of orbit, Ultraman creates havoc with Earth's oceans. The resulting flooding destroys the burial site of Black Manta's father. He's understandably a little pissed.
In Swordquest, the protagonists were destined to grow up as submissive servants in fear of the Big Bad... only to become emboldened to rebel against him only after one of his captains killed their foster parents in a moment of pettiness.
The Elseworlds storyline JLA: Created Equal has an interesting case of this; after most of Earth's male population is wiped out by a strange disease, the only two men to survive the virus are Superman and Lex Luthor (Superman because it couldn't get through his super-immune system and Luthor because he sealed himself away before he could be infected). While sperm samples from Superman are used to begin repopulating Earth, Luthor determines that Superman is still a carrier of the virus, forcing the Man of Steel to leave Earth so he doesn't kill his children. Years later, Luthor has manipulated several of the male children to see him as a 'saviour' against the 'oppression' of the women who are 'holding them back', even after Superman returns to Earth, having discovered a cure for the virus in his travels even if it can't remove the virus from Superman due to the same immune system that stopped the virus killing him in the first place. However, when Luthor attempts to kill Superman with kryptonite, the kryptonite poisoning actually weakens Superman's immune system just enough for the antivirus to 'infect' him, purging Superman of the virus and allowing him to work on safely raising both his own children and the children Luthor had created in a lab and kept contained until he had eliminated Superman's offspring.
In Hex Wives, Aaron goes to great lengths to make sure the witches don't accidentally cut themselves and thereby activate their Blood Magic. Then he tells Isadora to make sure she washes the black-handled knives by hand as putting them in the dishwasher blunts them. Isadora, who was already in a strange headspace, decides to cut herself to see what happens.
When Green Arrow and Black Canary got married, various parties attempted to use the wedding to their advantage by having Oliver Queen switched with the shape-shifter Everyman during the ceremony, the intention being that Everyman would pose as Green Arrow for a month to infiltrate the heroes and then fake his own death to drive Black Canary to the Amazons (now currently controlled by Granny Goodness). Unfortunately, Everyman was psychologically incapable of performing sexually on the wedding night which drove him to try and kill Black Canary instead, ruining the long-term plan as she killed him in self-defence and eventually tracked down her missing lover.
Billy Batson and the Magic of Shazam: Axe's command to a hypnotized Billy accidentally helped him discover that the Magic Lightning could break the spell, which he then used to free his sister Mary.
"The Super-Duel in Space": A shrunken Superman manages to infiltrate Brainiac's ship, but he is mistaken for an annoying fly for Brainiac, who tells his pet Koko to swat it. While fleeing from Koko, Superman flies into a Bottle-City which Brainiac was examining and finds Kandor, the last Kryptonian city which survived its planet's explosion thanks to Brainiac stealing it for his collection and was rescued by Superman thanks to Koko chasing after him.
In Two for the Death of One, Satanis and Syrene's magic war splits Superman into two "twins". When both Supermen face Satanis for the last time, the magic energies surrounding them merge into a giant energy Superman who attempts to kill Satanis. Satanis swiftly destroys the magic monster, but his spell reverts the original one which split Superman in two entities.
In The Unknown Supergirl, Kara Zor-El has lost her powers for some mysterious reason and does not know how to get them back. Right when she is about to give up her Supergirl identity, Mr. Mxyzptlk pops in Superman's Earth, thinking "Would not it be funny if I made an ordinary girl more powerful than Superman? Imagine how humiliated Superman will feel!", sees a girl -Kara- wearing a female version of Superman's costume and gives her Kryptonian powers. Thanks to him, Kara finally gets her powers back, and although his magic eventually wears off, her natural powers have returned by then (since her enemy Lesla-Lar, who had nullified them, is no longer around to screw her up).
In Green Lantern: Earth One, Hal Jordan, after his ring loses its power, is captured by the Manhunters and forced to work as a slave miner alongside many other aliens. Nonetheless, the Manhunters fail to take the ring from him and once it recharges, Hal stomps all over them.
