'''Polycarpus II''' (Gr: 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 of Byzantium|Felix]]. He was in office during the rule of Emperor Antonius Pius. His successor was [[Athenodorus of Byzantium|Athenodorus]].