Polycarpus II (Greek: Πολύκαρπος Β΄, d. 144) was the bishop of Byzantium. According to ancient sources, he remained in office for seventeen years, but Church historian Nikiforos Kallistos mentions that Polycarpus II was the bishop of Byzantium for three years (141-144 A.D). He succeeded Bishop Felix. He was in office during the rule of Emperor Antonius Pius. His successor was Athenodorus The relics of Polycarpus II were kept in a coffin made of marble.