PIRRO I, patriarch of COSTANTINOPOLI. - Successor of Sergio in the patriarchate (639), he died at Costantinopoli between 19 and 23 May 655. A changeable spirit, he began by supporting the Ekthesis of Eraclio in favour of Monophysitism.
Costanzo II, however, deposed him and exiled him to North Africa. Pope Teodoro wished P. to be judged in a council, but he embraced orthodoxy following a solemn disputation held at Cartagine (645) with St Massimo il Confessore. Having come to Rome, P. abjured Monothelitism before Pope Teodoro, who nevertheless had to excommunicate him later because he had fallen back into his former errors. The Lateran Council of 649 ratified the condemnation of P., who proposed a new formula of faith to Pope Eugenio I and again became, in December 654, the Monothelite patriarch of Costantinopoli. He was condemned by the Sixth Ecumenical Council (681). His works have almost entirely disappeared.