Originally a patriarch is a man who exercises autocratic authority over an extended family. See patriarchy.
Abraham, Isaac and Jacob are referred to as the three patriarchs of Judaism, and the period in which they lived is called the patriarchal period.
The word has also taken on other meanings. In particular, the highest-ranking bishops in Eastern Orthodoxy, Oriental Orthodoxy, the Catholic Communion, and the Assyrian Church of the East are called patriarchs.
Current Patriarchs in the Catholic Communion:
Historical Patriarchs in the Roman Catholic Church:
Current Patriarchs in the Eastern Orthodox Communion:
Current Patriarchs in Oriental Orthodox Churches
Patriarchs in Nestorian Churches