Stephen (Croatian: Stjepan) was a prelate of the Catholic Church who served as the bishop of Duvno from 1355 to 1362 and again in 1371. Stephen also administered the Diocese of Makarska after its bishop Valentine resigned in 1344 until his return to the Diocese in 1356.
Croatian archivist and historian Dominik Mandić could not find any documents in the Vatican archives regarding Stephen. Mandić and Ivan Ostojić write that he was from among the Split Benedictines. Valentine, the bishop of Makarska, resigned in 1344 due to unfavourable political situation after the patrons of the dioceses of Makarska and Duvno from the Šubić family have lost political power to Bosnian Kotromanić dynasty. The administration over the diocese was granted to Stephen. Stephen was mentioned as the bishop of Duvno in 1355 in an engraving on the walls of a chapel in the Sustjepan graveyard in Split, Croatia. The chapel itself was built in 1825, but the material from the much older Benedictine Abbey of Saint Stephen under Pines, including the inscription, was used in its construction. The abbey served as Stephen's residence until 1356, when it was granted to Valentine. That year, Valentine returned to Makarska as bishop after the territory of his diocese was given to King Louis I as a dowry of his wife Elizabeth of Bosnia of the Kotromanić dynasty.
Stephen was also mentioned in three documents of the chancellery of the Archdiocese of Split. In a charter of King Louis I from 1358, Stephen was mentioned among the witnesses, where he was referred to as the bishop of Duvno. He was mentioned as a witness again in 1361 on the occasion of the resignation of a priest of the churches of Saint John and Saint Euphemia before the Archbishop of Split Hugolin Branca. The next year, on 28 December 1362, the Archbishop mentioned Stephen as a bishop without a diocese and granted him the church of Saint Peter of Gumay in Sumpetar in the present-day Municipality of Dugi Rat. The circumstances in which Stephen lost his diocese between 1361 and 1362 are unknown. Since Stephen was mentioned with Archbishop Branca already in 1358, Slavko Kovačić considers that Stephen was his auxiliary bishop, who at the same time administered over the dioceses of Duvno and Makarska.
In 1371, Stephen was once again mentioned as the bishop of Duvno, this time as a witness in a document of the Benedictine monastery of Saint Chrysogonus in Zadar.