The Books of J.R.R. Tolkien 
Fiction based on any of the published written works of Tolkien.
Movies about Tolkien 
This category is for fanfiction based on film adaptations of Tolkien's work.
This category is for all non-fiction, including essays, research articles and tutorials.
This category is for artworks of all kinds, so long as they are based on Tolkien's works and world. This includes illustrations for fanfiction posted at this or other sites.
Challenge Stories 
This category is for stories written specifically for Challenges.
This category is for fanfiction which includes two or more fictional worlds, or the same world in differing times. At least one of those worlds must be primarily based on the works of Tolkien.