Tetralogy

A tetralogy (from Greek τετρα- , "four" and -λογία -logia, "discourse") is a compound work that is made up of four distinct works. The name comes from the Attic theater, in which a tetralogy was a group of three tragedies followed by a satyr play, all by one author, to be played in one sitting at the Dionysia as part of a competition.

In the classical period of literature, Shakespeare is known to have drafted a pair of tetralogies, the first consisting of the three Henry VI plays and Richard III, and the second consisting of Richard II, the two Henry IV plays, and Henry V.

As an alternative to "tetralogy", "quartet" is sometimes used, particularly for series of four books. The term "quadrilogy", basing the prefix on Latin prefix quadri- instead of the Greek prefix, and first recorded in 1865, has also been used for marketing series of movies, such as the Alien series.

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