Tetrarch

Tetrarch, Tetrarchs, or Tetrarchy may refer to:
 * Tetrarchy, the four co-emperors of the Roman Empire instituted by the Emperor Diocletian
 * Portrait of the Four Tetrarchs - a sculpture of the four co-emperors of the Roman Empire
 * Herodian Tetrarchy, formed by the sons of Herod the Great
 * Tetrarch, Military rank in ancient Greek armies
 * Tetrarch (novel), a 2003 novel by Ian Irvine
 * Light Tank Mk VII Tetrarch, a British light tank of World War II
 * The Tetrarch, a Thoroughbred racehorse
 * The Tetrarchs of Ancient Thessaly under Philip II of Macedon
 * The Tetrarchs of Galatia in Asia Minor
 * Tetrarches, a rank in the Byzantine army
 * Tetrarch, a 1981 fantasy novel by Alex Comfort
 * Tetrarch (band), a nu metal band from Atlanta, Georgia
 * Tetrarchy, a subdivision of the Royal Phalanx in 19th-century Greece
 * HMS Tetrarch is the name of the two vessels that have served in the Royal Navy