The Hobbit

The Hobbit is a prequel of sorts to the Lord of the Rings, or at least, that is how it seems today. At the time when LotR was being written, the new book (which went by various titles) was the sequel to The Hobbit; The Hobbit has since been eclipsed by its far more famous (and longer) sequel.

The two books form a sequel (of sorts) to the Silmarillion mythos; however, The Hobbit was not originally intended to be set in the same world as the Silmarillion tales, but simply borrowed some of the language to give the novel more depth, leading to some unresolved inconsistancies between the two.