Fan art, fan fiction, fan films, cosplay and fan games. These are just a handful of the ways that fans of fiction franchises choose to express their fandom aside from passive consumption. Not all fans have the gumption and initiative to go beyond consumption but those that do, often go the extra mile and make something that can sometimes rival the originals.
Fan creations are somewhat of a grey area in copyright law. While a lot of it is openly created and distributed, the vast majority of it is done without the express consent of the copyright owner. However, most of those copyright owners look the other way, but not always.