Parthenius III (Greek: Παρθένιος Γ΄; died 24 March 1657) was Ecumenical Patriarch of Constantinople in 1656–1657. In 1657 he was charged with treason by the Ottoman Sultan and hanged, after refusing to abjure his own Christian faith. He is hence revered as New Hieromartyr Parthenius III and his feast day in the Eastern Orthodox Church is March 24.