Trilogy is also the name for a $600 million modernization program for FBI computers.

A trilogy is a set of three works of art, usually literature or film, that develop a single theme even though they are generally created at different times. They may tell an extended story, such as Isaac Asimov's original Foundation series; or involve the same characters or the same setting, as in the Mars trilogy by Kim Stanley Robinson; or have only the most tenuous of connections, as in the surreal Nova trilogy novels of William S. Burroughs.

It is not uncommon for longer series to be created, such as The Alexandria Quartet novels by Lawrence Durrell or the open-ended series of James Bond movies. But the trilogy is the classic case of such extended series, perhaps reflecting a basic connection between human nature and the number three, or perhaps merely reflecting the difficulty of creating lots of variations of one theme.

In the Athens of Ancient Greece it was customary to exhibit on the same occasion three serious dramas, or a trilogy, at first connected by a sequence of subject, but afterward unconnected, and on distinct subjects, a fourth or satyric drama being also added, the characters of which were satyrs. Shakespeare's "Henry VI" may be called a trilogy.

Ideally, each work in a trilogy stands by itself, with the trilogy adding to the overall experience. However, a trilogy is sometimes just a larger work divided into three, so that the single members are not in themselves fully satisfying. Trilogies may arrive at three works for other reasons; for instance the original Foundation series was originally eight short stories and novelettes, and the division into books can be considered more or less accidental.

Some authors of popular trilogies may later extend the series by adding more works. This happened in the case of Asimov's Foundation series, which for many decades was just three books but was enlarged in the author's later life; and also in The Hitchhiker's Guide to the Galaxy, a series of five novels which the author Douglas Adams, for humorous effect, continued to dub a "trilogy" for the rest of his life. Similarily, the afterwards of Piers Anthony's Xanth books jokingly refer to those books as being 2 trilogies (both now rather overgrown).

Trilogies differ from a triptych, which is a set of three related or connected paintings that are created at one time and designed to be viewed as a single work.

Famous trilogies

Novels

• U.S.A., three novels by John dos Passos
• American Trilogy by Philip Roth including American Pastoral, I Married a Communist and The Human Stain
• The Gormenghast trilogy by Mervyn Peake
• The Salterton, Deptford and Cornish trilogies of Robertson Davies
• The Space Trilogy by C. S. Lewis
• The Condor Trilogy by Jin Yong: The Legend of the Condor Heroes (She Diao Ying Xiong Zhuan), The Return of the Condor Heroes (Shen Diao Xia Lu), and The Heavenly Sword and Dragon Saber (Yi Tian Tu Long Ji).

Note that this does not include The Lord of the Rings. Although initially published in three volumes, The Lord of the Rings is actually a single work rather than a trilogy. Tolkien himself divided the novel into six books plus five appendices in keeping with the literary device wherein Tolkien pretends to have "discovered" Middle-earth and to be describing it as befits a scholar of linguistics and ancient history. Ironically, in the 1960s when it burst into worldwide popularity, fans dubbed it "the trilogy" (or even the trilogy). It is also available in both one-volume and seven-volume editions.

Movies

• The Godfather movie trilogy by director Francis Ford Coppola
• Three Colors movie trilogy by director Krzysztof Kieslowski
• The Star Wars movies - now a double trilogy
• Indiana Jones movies - possibly a future tetralogy
• Peter Jackson's The Lord of the Rings movies
• Back to the Future Trilogy
• The Matrix trilogy
• The Terminator series
• Alien trilogy, plus one parody of the triplet
• The movies featuring the Hannibal Lecter character - actually a tetralogy, but including one remake, and soon to become a quintology

See also

• Tetralogy