Tolkien's legendarium is the body of J. R. R. Tolkien's mythopoeic writing, unpublished in his lifetime, that forms the background to his The Lord of the Rings, and which his son Christopher summarized in his compilation of The Silmarillion and documented in his 12-volume series The History of Middle-earth. The legendarium's origins reach back to 1914, when Tolkien began writing poems and story sketches, drawing maps, and inventing languages and names as a private project to create a unique English mythology. The earliest story drafts are from 1916; he revised and rewrote these for most of his adult life.

John Ronald Reuel Tolkien was an English writer and philologist. He was the author of the high fantasy works The Hobbit and The Lord of the Rings.