The highest-ranking bishops in Eastern Orthodoxy, Oriental Orthodoxy, the Catholic Church (above major archbishop and primate), the Hussite Church, Church of the East, and some Independent Catholic Churches are termed patriarchs (and in certain cases also popes – such as the Pope of Rome or Pope of Alexandria, and catholicoi – such as Catholicos Karekin II).

The word is derived from Greek πατριάρχης (patriarchēs), meaning "chief or father of a family", a compound of πατριά (patria), meaning "family", and ἄρχειν (archein), meaning "to rule".

Originally, a patriarch was a man who exercised autocratic authority as a pater familias over an extended family. The system of such rule of families by senior males is termed patriarchy. Historically, a patriarch has often been the logical choice to act as ethnarch of the community identified with his religious confession within a state or empire of a different creed (such as Christians within the Ottoman Empire). The term developed an ecclesiastical meaning within Christianity. The office and the ecclesiastical circumscription of a Christian patriarch is termed a patriarchate.

Abraham, Isaac, and Jacob are referred to as the three patriarchs of the people of Israel, and the period during which they lived is termed the Patriarchal Age. The word patriarch originally acquired its religious meaning in the Septuagint version of the Bible.