The Roman Catholic Suburbicarian Diocese of Ostia is an ecclesiastical territory located within the Metropolitan City of Rome in Italy. It is one of the seven suburbicarian dioceses. The incumbent Bishop is cardinal Giovanni Battista Re. Since 1150, its bishop has been the Dean of the College of Cardinals, Its Cathedral is Basilica di Sant'Aurea.
From 1105 to 1914, the diocese was merged with the Suburbicarian Diocese of Velletri. In 1962, the Diocese of Ostia was brought under the direct administration of the Diocese of Rome.
Bishops
Bishops of Ostia (-1057)
[Maximus (259)]
... Maximus (313) Florentius (366) ... Bonus (487). Bellator (499) Aristus (502) ... Amabile (649) ... Andrea(s) (680) ... Sissinio 732 – before 745 Theodorus (745) George I, 753–786 ... Gregory I, 787 – before 804 Bernard 804–805 Peter I 805 – before 826 Cesareo 826–854 Megisto (or Leo I), 854–868 Donatus, 868–870 sede vacante 870–878 Eugenius, 878–898 Stephen, 898–900 Guido I, 900–946 Benigno, 946–960 Siccone, 960–963 Gregory II, 964–969 Leo II, 969–983 vacant 983–996 Azzone I, 996 Gregory III, 998–1012 Azzone II, 1012–1021 Peter III, 1021–1037 Benedict, 1044–1050 John I, 1050–1058
Bishops of Ostia and Velletri (1057-1378)
Peter IV Damiani, 1057–1072
Gerald of Ostia, 1072–1077
Odo I de Lagery, 1078–1088 (became Pope Urban II) Odo II, 1088–1102 Leo of Ostia, ca. 1103–1115 Lamberto Scannabecchi, 1116–1124 (later Pope Honorius II) Giovanni of Camaldoli, 1126–1134 Drogo of Champagne, 1136–1138 Alberic, 1138–1148 Guido II de Summa, 1149–1151 Hugo, 1151–1158 Ubaldo Allucingoli, 1159–1181/84 (became Pope Lucius III in 1181) Theobald, 1184–1188 Ottaviano di Paoli, 1189–1206 Ugolino di Conti 1206–1227/31 (became Pope Gregory IX) Rinaldo dei Signori di Ienne, 1231–1254/61 (became Pope Alexander IV in 1254) Hugh of Saint-Cher 1261–1262 Enrico Bartolomei 1262–1271 vacant 1271–1273 Peter VI de Tarentaise, 1273–1276 (later Pope Innocent V, † 1276) vacant 1276–1278 Latino Malabranca Orsini, 1278–1294 Hugh Aycelin, 1294–1297 Leonardo Patrasso, apostolic administrator 1298–1299 Niccolo I Boccasini, 1300–1303 (became Pope Benedict XI) Niccolò Albertini, 1303–1321 Regnaud de La Porte, 1321–1325 vacant 1325–1327 Bertrand du Pouget, 1327–1352 Étienne Aubert, 1352 Pierre Bertrand de Colombier, 1353–1361 Andouin Aubert, 1361–1363 Hélias de Saint-Yrieix, 1363–1367 Guillaume de la Sudrie, 1367–1373 Peter d'Estaing, O.S.B. 1373–1377 Bertrand Lagier, 1378 (sided with of Avignon in the Great Schism)
Western Schism
Obedience of Rome (1378–1415) (actually in control of Ostia) Philippe of Alençon, 1388–1397 (also Cardinal-bishop of Sabina, 1380–1388) Angelo Acciaioli, 1405–1408
Obedience of Avignon (1378–1429) Bertrand Lagier (1378–1392) John de Neufchatel (1392–1398) Leonardo Rossi da Giffoni (1398–1405) Jean-Allarmet de Brogny (1405–1408) Julian Lobera y Valtierra (1423–1429)
Obedience of Pisa (1409–1415) Jean-Allarmet de Brogny (1409–1415)
Bishops of Ostia and Velletri (1415-1914)