Rita Skeeter is the magical world's resident rumourmonger - a journalist whose articles are read by the masses. She will do anything for a story and is an unregistered animagus, able to turn into a bug at will. She earns, with her blatantly untrue stories, in Book 4 Hermione's undying hatred and something similar from Harry, Ron, and even Hagrid.
Her tools include a quill which writes in journalistic style without help and some ludicrous clothing. Very pleasent in public, she can also turn very nasty. She is captured as a bug by Hermione at the end of Book 4.