A tetralogy is a compound work that is made up of four (numerical prefix tetra-) 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.
Antiphon of Rhamnus, an orator, taught his students with Tetralogies, each one consisting of four speeches: the prosecutor's opening speech, the first speech for the defence, the prosecutor's reply, and the defendant's conclusion. Three of Antiphon's tetralogies survive. In more recent times, Shakespeare wrote two 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. Richard Wagner's Der Ring des Nibelungen ("The Ring of the Nibelung" or "The Ring Cycle") is also referred to as a tetralogy.
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.
Examples of works which have been described as tetralogies are as follows:
Literary works 
In literature, the term tetralogy has been applied to series of novels, plays and poetry with four entries. These include the following:
- Major tetralogy: Richard II; Henry IV, Part 1; Henry IV, Part 2; Henry V
- Minor tetralogy: Henry VI, Part 1; Henry VI, Part 2; Henry VI, Part 3; Richard III
- E. E. Smith's Skylark series
- Harry Turtledove's Settling Accounts
- John Updike's Rabbit series (Rabbit, Run; Rabbit Redux; Rabbit is Rich, Rabbit at Rest) There is also (Rabbit Remembered), the fifth part of the series.
- T. H. White's The Once and Future King
- Gene Wolfe's Book of the New Sun and Book of the Long Sun
- Sigrid Undset's The Master of Hestviken tetralogy, "The Axe", "The Snake Pit", "In the Wilderness", "The Son Avenger", published in 1925 and 1927.
- Lawrence Durrell's The Alexandria Quartet consists of Justine (1956), Balthazar (1958), Mountolive (1958), Clea (1960)
Historical works 
See also 
- ^ Rush Rehm. Greek Tragic Theater. Routledge, 1994. Page 16.
- ^ C. M. Bowra. Landmarks in Greek Literature. Weidenfeld and Nicholson, 1966. Pages 236-7.
- ^ Victor L. Cahn. Shakespeare the playwright: a companion to the complete tragedies, histories, comedies, and romances. Greenwood, 1991.
- ^ Hans von Wolzogen. Guide to the music of Richard Wagner's tetralogy: The ring of the Nibelung. A thematic key. Translated by Nathan Haskell Dole. G. Schirmer, New York, 1895.
- ^ Simpson, J.A., and Weiner, E.S.C. (eds.) The Oxford English Dictionary. 2nd ed. 1989. Oxford. Clarendon Press. "quadri-"
- ^ http://www.urbandictionary.com/define.php?term=quadrilogy
- ^ Heuman, Fred S. (Spring, 1982). "Some Major Biblical Sources in Thomas Mann's Joseph Tetralogy". Notre Dame English Journal 14 (2): 87–112. Retrieved December 18, 2011.
- ^ ReadingMarksonReading: David Markson Marginalia Website:
"Markson’s writing was so informed by his reading—especially his late tetralogy (The Notecard Quartet, as those last four novels have been called) which is filled wholly with the cultural detritus he’d pick up from his voracious reading."
- ^ 
- ^ a b Shakespeare in Performance: Film
- ^ Discussion of this Nobel laureate's two major works, this tetralogy and the trilogy Kristin Lavransdatter