Some of the other characters may have been brutalized in terms of how they were portrayed in the films, but at least they made it to the screen. Peeves was originally intended to be featured in the movies, and was performed by Rik Mayall, but was then left on the cutting room floor. It seems likely that Peeves was cut simply because the technology wasn't where it needed to be to see the poltergeist fully realized, but it's still a shame that we never got to see him on screen. He added to the charm and eccentricity of Hogwarts (because it's not enough to have to deal with moving staircases and walls pretending to be doors, you should also have to worry about a ghost throwing water balloons at you). His absence is most missed in Order of the Phoenix, when he valiantly and hilariously joined in the battle against Umbridge. We would have loved to hear the immortal line from the Weasley twins, "Give her hell from us, Peeves," in the movie.