Legendarium

A legendarium is a book or series of books consisting of a collection of legends.

The word was also used by J. R. R. Tolkien to describe his artificial mythology of Middle-earth. Tolkien's great mythological tales of Middle-earth are meant to be taken, fictitiously, as an ancient history of the Earth, particularly of Europe, from several thousand years before the modern era. Tolkien's legendarium is often called "Middle-earth mythology".