Green Lantern went nuts, killed a bunch of Green Lanterns, all the Guardians, and became Parallax (or got possessed by some sort of bug thing, whatever, it's all the same). He then tried to rewrite the universe, make it better, bring back the alternate Earths, etc.
His reason for all this? Because the Cyborg Superman and Mongul destroyed Coast City.
Oh, but you say that's not Superman's fault, it was Cyborg and Mongul.
Hank Henshaw was poisoned by radiation and died, hating Superman for not being able to save him. His consciousness lived on, able to inhabit machines, including Kal-El's rocketship, which Superman had stashed in orbit for safe keeping. From this, he took Kryptonian metal samples and Superman's DNA, and fashioned a body, claiming to be the true Superman after his Death.
Mongul was the deposed ruler of Warworld. Deposed by Superman, who escaped his gladiatorial games and stripped him of his position. He vowed revenge and wanted to create a new Warworld, preferrably out of Earth. Teaming up with Cyborg, they chose to start with Coast City.
Two Superman villains blow up Green Lantern's hometown because they've got a beef with the Man of Steel, and because he just left stuff lying around (the rocket, Mongul), unguarded and disregarded. Real careless, Kal-El.
This means that Zero Hour was Superman's fault, too. Honestly, I'd leave that off my resumé, Clark. If you're going to be ashamed about a Crisis event, be ashamed about that one.
And "War of the Gods." But I digress.
Of course, there's also Superboy, who got taken over by Luthor and went berserk. Being taken over? Going berserk? It's in Superman's DNA!
Like original, like clone, I guess.