The reason why Dudley's on this list can be summed up in one simple line: "I don't think you're a waste of space." Would that have been so difficult, WB? Because Dudley is pretty well portrayed throughout the film series - he appears sporadically, but he's there when it makes sense for him to be there. Everything is in the films except for his redemption, a scene which would have taken mere minutes but added so much to the film. This is probably what was cut in favor of that awkward scene with Harry creepily zipping up Ginny's dress. When you grow up, you realize that the "enemies" you had when you were a kid were really just people, not monsters. Even though Dudley was a big bully as a child and teenager, he was still capable of understanding that Harry was not the freak that his parents had always portrayed him as. He recognized his cousin's value, and was willing to part on good terms. Just like Dumbledore said in the sixth book, Dudley was just as much of a victim of the Dursleys' treatment as Harry was.