On the site Pottermore, Joan Rowling wrote that from all the characters killed by her most regrets the death of Florean Fortescia - the owner of the ice cream cafe in the oblique alley. According to the writer, the death of other heroes was justified by the plot, and the ice cream died, because she just drove himself into the corner. "Initially, I planned that Florean would be a kind of source of horses for Harry in the rays of the secrets of death gifts. That is why I introduced them so early. But later I decided that Fineas Black was better suited for the role of the conductor. And it seems I killed Florean without any reason. He is not the first one who killed Wolan de Mort, but the only one, because of whose death I feel guilty, because it was whole of my fault, "Rowling admitted.
On the Pottermore portal, the writer publishes additional information about the characters, the history of the magical world and other interesting additions to the original series of books. But she did not explain what the death of such heroes as Fred, Dobby, Lupine, Tonks and others was justified.