Otto II employed monks among his top political advisers, including Ekkehard I and Majolus of Cluny. One of the most important such monks was John Philagathus (the future Antipope John XVI). Of Greek descent, John was the personal chaplain of Otto II's wife Theophanu, accompanying her when she traveled from Constantinople to marry Otto II. Otto II appointed him as his Imperial Chancellor from 980 to 982, as well as abbot of Nonantola Abbey. Following Otto II's death in 983, Theophanu, as her son Otto III's regent, would name John as Otto III's tutor. She would later appoint John as the bishop of Piacenza, and would send him to Constantinople to arrange for a marriage between Otto III and a Byzantine princess.