Byllis, a titular see of Epirus Nova (Albania), whose title is often added to that of Apollonia among the suffragans of Dyrrachium (Durazzo). It was situated west of Avlona, on the coast, near the modern village Gradica, or Gradiste, a Slav name substituted in later episcopal “Notitiae” for the old Illyrian name Byllis (Not. episc. III, 620; X, 702). Hierocles (653, 4) knows only of Byllis. Felix, Bishop of Apollonia and Byllis, was present at the Council of Ephesus, in 431, At Chalcedon in 451, Eusebius subscribes simply as Bishop of Apollonia; on the other hand, Philocharis subscribes as Bishop of Byllis only in the letter of the bishops of Epirus Nova to the Emperor Leo, (458).