Unrepentant mass murderer of fictional characters J.K. Rowling has always maintained that killing off so many "Harry Potter" peeps was a difficult but necessary task: that they had to die, all of them, in order to move the story forward.
But it turns out, the "Harry Potter" author did do one killing that she feels really, really bad about: A minor character named Florean Fortescue, who we met in "Harry Potter and the Prisoner of Azkaban."
"I seemed to have him kidnapped and killed for no good reason," Rowling wrote on Pottermore. "He is not the first wizard whom Voldemort murdered because he knew too much (or too little), but he is the only one I feel guilty about, because it was all my fault."
Apparently, the author originally intended for Florean to play a bigger part in the final "Harry Potter" book, but his role was overtaken by a portrait of Phineas Nigellus Black -- and so Florean was never rescued from his kidnapping situation, a casualty of poor plotting. But while J.K. Rowling clearly feels awful about poor Florean, we can think of a few characters who are more deserving of a guilty conscience:
The Death Eaters had already taken plenty of Weasley from the world when a curse claimed George's ear at the start of the seventh book. There was no need to kill of poor, sweet, fun-loving Fred at the Battle of Hogwarts, too. No need, d'you hear? The ear was enough!
Remus Lupin and Nymphadora Tonks
Even if a family or two had to be shattered in the course of saving the wizarding world from Voldemort, it was hardly necessary to take both Lupin and Tonks, and leave their infant son parentless. That's just cold.
It was Harry Potter's tearful burial of Dobby that convinced Griphook the goblin he was a different kind of wizard, leading to the reclamation of a Horcrux from inside the vault at Gringotts. Only let's be honest, Griphook would have been just as impressed if he'd watched Harry nursing a wounded Dobby back to health, which means the elf died for nothing.
Sorry, still not over it.