Everyone loves an origin story, and when it comes to a person's beloved comic book superheroes and villains, those stories can be what ultimately brought the fan to the franchise. While most characters have a detailed, and well-understood origin written years before, some find their way to a retcon or revamp, and not everyone is happy with the changes.
On the one hand, it makes sense that a character created nearly a century ago would need some updating. After all, the world is much different now than it was in the 1940s-1980s, and comic book creators understand this all too well.
Still, it can be frustrating when a character fans have been reading and enjoying without complaint for decades suddenly gets a complete overhaul. All the big publishers are guilty of doing this in one way or another, and it's always a hit or miss as to whether or not the changes will last.
Typically, a change to an origin story can annoy a longtime fan, but every so often, a change will infuriate them to the point of rage-quitting a series. These are the changes that truly made the fans angry, and while some may have liked them, many more did not.
10. Harley Quinn
Harley Quinn is unlike any of the other characters on this list due to the fact that her first appearance wasn't in a comic book, it was on Batman: The Animated Series. She appeared in the episode "Joker's Favor" in 1992, and wasn't placed into a comic book until the following year in The Batman Adventures #12.
Since then, she's gone on to become one of Bats' best characters, and thanks to Margot Robbie's stellar performances as Quinn on the big screen, she's also now one of the most well-known of all Batman's rogues. Her origin story was widely appreciated by fans, but it wasn't safe from a few tweaks.
Originally, her origin was told in the 1994 graphic novel The Batman Adventures: Mad Love, which showed how Dr. Harleen Quinzel, Ph.D., fell in love with the Joker while she was working in Arkham Asylum. She helped him escape and became his follower/lover.
When the New 52 reimagined the character, it tweaked one thing that a lot of fans didn't much care for. The new story showed her initiation into the Joker's embrace by having him throw her into the same vat of chemicals that turned him into the Clown Prince of Crime. (It was later revealed in Death of the Family that the Joker had also kept "other Harleys" before Quinn came into the picture.)
Some fans liked the change, and it was reflected in the film Suicide Squad, but many didn't like it at all.