heptalogy

A heptalogy is a set of seven works of art that are comprised by a common storyline. Trilogies and Tetralogies are the most common, but some heptalogies known to general audiences are the Harry Potter series of books and movies, the Police Academy movies, the Chronicles of Narnia and Stephen King's The Dark Tower. Other well-known heptalogies are the as-yet unfinished Keys to the Kingdom series by Garth Nix, and A Song of Ice and Fire by George R.R. Martin.
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