John XII may refer to:
Pope John XII, ruled 955–964 John XII bar Maʿdani, Syriac Orthodox Patriarch of Antioch 1252–1263 John XII of Constantinople, Ecumenical Patriarch 1294–1303 Pope John XII of Alexandria, ruled 1480–1483 John XII Peter El Hajj, Maronite Patriarch of Antioch 1890–1898
See also John 12, the twelfth chapter of the Gospel of John