Heptalogy
From Wikipedia, the free encyclopedia
An heptalogy is a set of seven works of art that comprise a common storyline. Trilogies and Tetralogies are the most common, and the only heptalogies known to general audiences are the Harry Potter series of books and the Chronicles of Narnia. Other well-known heptalogies are Stephen King's The Dark Tower and the yet unfinished Keys to the Kingdom series by Garth Nix.