IV plays, and Henry V. As an alternative to "tetralogy", "quartet" is sometimes used, particularly for series of four books. The term "quadrilogy", using the Latin prefix quadri- instead of the Greek, and first recorded in 1865, has also been used for marketing the Alien movies. See also Sequel List of film series with four entries Trilogy References Tetralogies Literary tetralogies Literary series Film series Musical forms Narrative forms