David Day is the author of five major books on the world of J.R.R. Tolkien, including Guide to Tolkien's World: A Bestiary and A Guide to Tolkien. Together with Tolkien: The Illustrated Encyclopedia, these books have been translated into sixteen languages, and have sold in excess of two million copies. A Canadian living in Toronto, Day has also published over 30 other books of mythology, history, fantasy, fiction, and poetry, for both adults and children.