Retcons. We love 'em, we hate 'em, we love to hate 'em. But sometimes, they go above and beyond the pale and become so weird that we have to talk about them. So I would like to do that.N
Note: These aren't necessarily the BEST or WORST retcons, they're just the ones that I found most interesting. So sit back, relax, and enjoy. Unless some god of time rewrote spacetime to make you unable to do that.
The Original Story: In the '90s, DC Comics decided that Hal Jordan was boring and they needed to get rid of him. How much of that is owed to his years of being written by a pedophile (Look up what Gerard Jones is doing now) and how much is owed to Hal Jordan's actual boring-ness (he kind of is) is up to you.
Regardless, the outcome was the same: He had to go. So DC had him go completely bug-f**k insane, kill all the other Green Lanterns, and dub himself Parallax. He then became a straight-up supervillain for a while and let underrated Green Lantern Kyle Rayner take up the mantle. Hal kept being crazy until the sun was eaten by a space monster, and he died reigniting it.
The Retcon: A space bug did it. Yeah, it wasn't Hal. A giant yellow space bug named Parallax possessed him and stripped him of all responsibility.
That's my favorite excuse for when I make a mistake. "Yes, honey, I know I was supposed to make an appointment with my therapist this morning, but I was possessed by a space bug and instead watched all of American Horror Story, a show I don't even like."