Beth March, Little Women
This great media tragedy has been so deeply written into society that it even became a joke on the show Friends. The saddest part of Louisa May Alcott's novel (and in the recent Greta Gerwig film adaptation) is Beth dying from scarlet fever before she got to grow up. This character was so pure that people had no idea how to react when she died.
Jack Dawson, Titanic
There was room on that raft for Jack. We're sick of ignoring the obvious anymore. Rose could have spared Jack's life and we wouldn't have to be writing about this at all.