Tolkien's earliest novel was The Hobbit; or There and Back Again, published in 1937.

The Hobbit serves as an effective prelude to the saga of The Lord of the Rings and introduces a number of characters from the latter work, including Bilbo Baggins (Frodo's uncle), Gloin the Dwarf (Gimli's father), and the wise sorcerer Gandalf. Perhaps more significantly, Tolkein introduces the One Ring by narrating the tale of its change of ownership to Bilbo Baggins from Gollum, who had kept it hidden in a cavern beneath a mountain until even memory of the artifact had all but ceased to exist.

The Return of the King is not actually a novel in itself, but is instead the first part of The Lord of the Rings, a novel in six "books" and generally published in three volumes.

The Fellowship of the Ring (1954), which consists of the first two books...