Isaac Komnenos or Comnenus (Greek: Ἰσαάκιος Κομνηνός, translit. Isaakios Komnēnos; c. 1113 – after 1146), was the third son of Byzantine Emperor John II Komnenos by Irene of Hungary. He was bypassed by his father in favour of his younger brother Manuel I Komnenos for the succession, leading to a tense relationship between the two brothers after. He participated in the campaigns of his father and brother in Asia Minor, and was a fervent adherent of Patriarch Cosmas II of Constantinople, but little else is known about his life.