OTTAVIANO DI MONTICELLI (da MONTECELIO, near Tivoli). - Antipope under the name of Vittore IV (in fact he should have been V). Son of Giovanni Maledetto, of the Monticelli family, related to the royal families of Spain and France, in 1138 he was made cardinal of the title of S. Cecilia. In 1143 Celestino II employed him to negotiate peace with Ruggero II at Palermo. When the Pontiff died during the negotiations, O. was sent by the King to the newly elected Lucio II to induce him to a direct meeting.
Upon the death of Adriano IV (first week of September 1159), he was elected pope by a minority of the cardinals assembled in conclave, against the legitimate Rolando Bandinelli (Alessandro III). Imprisoned, with the help of the imperial troops to whose
party O. inclined, the legitimate Pontiff was freed after a popular insurrection and consecrated at Ninfa on 20 September; while O. had himself consecrated at Farfa on 4 October. Whereas almost all the States recognized Alessandro III as legitimate, the Empire supported O. Barbarossa therefore convened a Synod at Pavia to proclaim his legitimacy. But toward the end of the same year the Roman Senate also sided with Alessandro, who was able to return to Rome. O. died at Lucca on 20 April 1164.