John XII may refer to:

Patriarch John XII may refer to:

John XIII bar Ma'dani was the Patriarch of Antioch, and head of the Syriac Orthodox Church from 1252 until his death in 1263.

John XII (? – after 1308) was the Ecumenical Patriarch of Constantinople from 1294 to 1303. John XII was born in Sozopolis on the western Black Sea coast (now Sozopol, Bulgaria ). Prior to becoming patriarch, he was known as Kosmas. He crowned Michael IX as co-emperor on 21 May 1294. He led a coalition of bishops against Andronicus II's attempt to use the power of the Church to suppress uprisings.

Pope John XII of Alexandria, was the 93rd Pope of Alexandria and Patriarch of the See of St. Mark.