| Living Prelates (Total 5669) * |
  Bishop Servilien Nzakamwita (82), Bishop emeritus of Byumba (Rwanda) |
  Cardinal Dieudonné Nzapalainga, C.S.Sp. (58), Cardinal-Priest of S. Andrea della Valle and Metropolitan Archbishop of Bangui (Central African Republic) |
  Bishop Blaise Nzeyimana (70), Bishop of Ruyigi (Burundi) |
 Bishop Severin Nziengui Mangandza, C.S.Sp. (55), Vicar Apostolic of Makokou (Gabon) |
 Bishop Eusebius Alfred Nzigilwa (58), Bishop of Mpanda (Tanzania) and Vice-President of Tanzania Episcopal Conference |
 Bishop Daniel Nzika (54), Bishop of Impfondo (Congo-Brazzaville) |
 Bishop Mark Maigida Nzukwein (55), Bishop of Wukari (Nigeria) |
  Archbishop Brendan Michael O’Brien (81), Metropolitan Archbishop emeritus of Kingston (Canada) |
  Cardinal Edwin Frederick O’Brien (86), Cardinal-Priest of S. Sebastiano al Palatino pro hac vice Title, Metropolitan Archbishop emeritus of Baltimore (USA) and Grand Master emeritus of Equestrian Order of the Holy Sepulchre of Jerusalem (Knights of the Holy Sepulchre) |
| Bishop David Michael O’Connell, C.M. (70), Bishop of Trenton (USA) |
 Bishop Mark O’Connell (60), Titular Bishop of Gigthi and Auxiliary Bishop of Boston (USA) |
 Bishop Bernard Cyril O’Grady, O.P. (93), Bishop emeritus of Gizo (Solomon Islands) |
 Bishop John Joseph O’Hara (79), Titular Bishop of Ath Truim and Auxiliary Bishop emeritus of New York (USA) |
 Bishop Gregory O’Kelly, S.J. (83), Bishop emeritus of Port Pirie (Australia) |
 Cardinal Seán Patrick O’Malley, O.F.M. Cap. (80), Cardinal-Priest of S. Maria della Vittoria, President of Pontifical Commission for the Protection of Minors, Member of Council of Cardinals and Metropolitan Archbishop emeritus of Boston (USA) |
| Bishop Timothy James O’Malley (65), Titular Bishop of Numida and Auxiliary Bishop of Chicago (USA) |
 Bishop Noel Charles O’Regan, S.M.A. (83), Bishop emeritus of Ndola (Zambia) |
 Archbishop Patrick Michael O’Regan (66), Metropolitan Archbishop of Adelaide (Australia) |
 Bishop Colm O’Reilly (90), Bishop emeritus of Ardagh (Ireland) |
| Archbishop Kieran O’Reilly, S.M.A. (72), Metropolitan Archbishop of Cashel and Emly (Ireland) |
| Bishop Philip Leo O’Reilly (81), Bishop emeritus of Kilmore (Ireland) |
 Archbishop Mark O’Toole (61), Metropolitan Archbishop of Cardiff–Menevia (Wales) |
 Bishop David James Oakley (69), Bishop of Northampton (England) |
 Bishop John Oballa Owaa (66), Bishop of Ngong (Kenya) |
 Archbishop Ildefonso Obama Obono (87), Metropolitan Archbishop emeritus of Malabo (Equatorial Guinea) |
| Bishop Joseph Obanyi Sagwe (57), Bishop of Kakamega (Kenya) |
 Archbishop Emmanuel Obbo, A.J. (72), Metropolitan Archbishop of Tororo (Uganda) |
| Archbishop Anthony John Valentine Obinna (78), Metropolitan Archbishop emeritus of Owerri (Nigeria) |
| Bishop Ernest Anaezichukwu Obodo (58), Titular Bishop of Mediana and Auxiliary Bishop of Enugu (Nigeria) |
 Bishop Celestino Ocampo Gaona (63), Bishop of Carapeguá (Paraguay) |
 Bishop Joel Ocampo Gorostieta (61), Bishop of Ciudad Altamirano (Mexico) |
 Bishop Luisito Audal Occiano (53), Bishop of Virac (Philippines) |
 Bishop-elect Marek Ochlak, O.M.I. (59), Bishop of Fenoarivo Atsinanana (Madagascar) |
| Bishop Armando Xavier Ochoa (82), Bishop emeritus of Fresno (USA) |
 Bishop Víctor Manuel Ochoa Cadavid (62), Military Ordinary of Colombia (Colombia) |
 Bishop Manuel Ochogavía Barahona, O.S.A. (57), Bishop of Colón–Kuna Yala (Panama) and General Secretary of Episcopal Conference of Panama |
| Archbishop John Baptist Odama (77), Metropolitan Archbishop emeritus of Gulu (Uganda) |
 Bishop Sławomir Oder (64), Bishop of Gliwice (Poland) |
| Bishop Peter Kayode Odetoyinbo (61), Bishop of Abeokuta (Nigeria) |
| Bishop Sabino Ocan Odoki (67), Bishop of Arua (Uganda) |
| Bishop Henry Juma Odonya (48), Bishop of Kitale (Kenya) |
| Bishop Euzébius Chinekezy Ogbonna Managwu (65), Bishop of Port-Gentil (Gabon) |
 Bishop Óscar Vicente Ojea Quintana (78), Bishop emeritus of San Isidro (Argentina) |
| Bishop Crispin Ojeda Márquez (73), Bishop of Tehuantepec (Mexico) |
 Archbishop Simon Ok Hyun-jjn (옥현진 시몬 / 玉賢進) (57), Metropolitan Archbishop of Gwangju 광주 (South Korea) and General Secretary of Catholic Bishops’ Conference of Korea |
| Bishop Hilary Paul Odili Okeke (78), Bishop emeritus of Nnewi (Nigeria) |
| Archbishop Valerian Maduka Okeke (71), Metropolitan Archbishop of Onitsha (Nigeria) |
| Bishop Francis Emmanuel Ogbonna Okobo (88), Bishop emeritus of Nsukka (Nigeria) |
| Cardinal Anthony Olubunmi Okogie (88), Cardinal-Priest of S. Maria del Monte Carmelo a Mostacciano, Metropolitan Archbishop emeritus of Lagos (Nigeria) and former Member of Council of Cardinals for the Study of Organisational and Economic Problems of the Apostolic See |
| Archbishop Jude Thaddeus Okolo (68), Titular Archbishop of Novica and Apostolic Nuncio to Czech Republic |
| Bishop Emmanuel Okombo Wandera (82), Bishop emeritus of Kericho (Kenya) |
| Bishop Michael Nnachi Okoro (84), Bishop emeritus of Abakaliki (Nigeria) |
| Archbishop Zacchaeus Okoth (82), Metropolitan Archbishop emeritus of Kisumu (Kenya) |
| Bishop John Ifeanyichukwu Okoye (74), Bishop of Awgu (Nigeria) |
| Bishop Jonas Benson Okoye (62), Bishop of Nnewi (Nigeria) |
| Cardinal Peter Ebere Okpaleke (62), Cardinal-Priest of Ss. Martiri dell’Uganda a Poggio Ameno and Bishop of Ekwulobia (Nigeria) |
| Bishop Arkadiusz Okroj (57), Bishop of Toruń (Poland) |
| Bishop Orlando Olave Villanoba (56), Bishop of Ocaña (Colombia) |
| Archbishop Miguel Angel Olaverri Arroniz, S.D.B. (77), Metropolitan Archbishop emeritus of Pointe-Noire (Congo-Brazzaville) |
 Bishop Francesco Oliva (74), Bishop of Locri–Gerace (Italy) |
 Bishop Ivanildo Oliveira Almeida (53), Bishop of Cametá (Brazil) |
| Archbishop Walmor Oliveira de Azevedo (71), Metropolitan Archbishop of Belo Horizonte (Brazil) and Ordinary of Ordinariato para os Fiéis de Ritos Orientais no Brasil of the Eastern Rite (Brazil) |
| Bishop José Geraldo Oliveira do Valle, C.S.S. (95), Bishop emeritus of Guaxupé (Brazil) |
| Bishop José Otacio Oliveira Guedes (51), Titular Bishop of Severiana and Auxiliary Bishop of Belo Horizonte (Brazil) |
 Bishop Juan Bautista Tomás Oliver Climent, O.F.M. (73), Titular Bishop of Legis Volumni and Vicar Apostolic emeritus of Requena (Peru) |
| Archbishop João Bosco Óliver de Faria (85), Metropolitan Archbishop emeritus of Diamantina (Brazil) |
 Bishop Victorio Oliver Domingo (95), Bishop emeritus of Orihuela–Alicante (Spain) |
| Bishop Santiago Olivera (66), Military Ordinary of Argentina (Argentina) |
| Bishop Mario Oliveri (81), Bishop emeritus of Albenga–Imperia (Italy) |
| Bishop Donato Oliverio (69), Bishop of Lungro of the Italo-Albanese (Italy) |
| Bishop Derio Olivero (64), Bishop of Pinerolo (Italy) |
 Bishop Paulinus Yan Olla, M.S.F. (61), Bishop of Tanjung Selor (Indonesia) |
| Bishop Pedro María Olmedo Rivero, C.M.F. (80), Bishop-Prelate emeritus of Humahuaca (Argentina) |
| Bishop Thomas James Olmsted (78), Bishop emeritus of Phoenix (USA) |
| Bishop Martin Dada Abejide Olorunmolu (76), Bishop of Lokoja (Nigeria) |
| Bishop Michael Fors Olson (58), Bishop of Fort Worth (USA) |
| Bishop Grzegorz Olszowski (58), Titular Bishop of Rhoga and Auxiliary Bishop of Katowice (Poland) |
| Cardinal Juan José Omella Omella (79), Cardinal-Priest of S. Croce in Gerusalemme, Metropolitan Archbishop of Barcelona (Spain) and Member of Council of Cardinals |
| Bishop Callistus Valentine Chukwuma Onaga (66), Bishop of Enugu (Nigeria) |
| Bishop Godfrey Igwebuike Onah (68), Bishop of Nsukka (Nigeria) |
| Cardinal John Olorunfemi Onaiyekan (81), Cardinal-Priest of S. Saturnino and Metropolitan Archbishop emeritus of Abuja (Nigeria) |
| Bishop Jean-Vincent Ondo Eyene (65), Bishop of Oyem (Gabon) and President of Episcopal Conference of Gabon |
| Bishop Honesto Flores Ongtioco (76), Bishop emeritus of Cubao (Philippines) |
 Bishop Gonzalo Alfredo Ontiveros Vivas (56), Vicar Apostolic of Caroní (Venezuela) |
 Bishop John Opoku-Agyemang (67), Bishop of Konongo–Mampong (Ghana) |
| Bishop Radosław Orchowicz (55), Titular Bishop of Surista and Auxiliary Bishop of Gniezno (Poland) |
 Bishop Ángel Maximiliano Ordoñez Sigcho (53), Titular Bishop of Phelbes and Auxiliary Bishop of Quito (Ecuador) |
| Bishop Edson José Oriolo dos Santos (60), Bishop of Leopoldina (Brazil) |
| Bishop Giuseppe Orlandoni (86), Bishop emeritus of Senigallia (Italy) |
 Bishop José Ornelas Carvalho, S.C.I. (71), Bishop of Leiria–Fátima (Portugal) and President of Episcopal Conference of Portugal |
| Bishop Vincenzo Carmine Orofino (71), Bishop of Tursi–Lagonegro (Italy) |
 Bishop Domingo Oropesa Lorente (74), Bishop of Cienfuegos (Cuba) |
 Archbishop Ján Orosch (71), Archbishop of Trnava (Slovakia) |
 Bishop Atanáz Orosz (65), Bishop of Miskolc of the Hungarians (Hungary) |
| Bishop Francisco Jesús Orozco Mengíbar (55), Bishop of Guadix (Spain) |
| Bishop Guillermo Orozco Montoya (78), Bishop emeritus of Girardota (Colombia) |
| Bishop César Alfonso Ortega Díaz (56), Bishop of Linares (Mexico) |
| Archbishop Alberto Ortega Martín (62), Titular Archbishop of Midila and Apostolic Nuncio to Venezuela |
| Bishop Fernando Ortega Ortega (51), Titular Bishop of Thizica and Auxiliary Bishop of Cuenca (Ecuador) |
| Bishop José María Ortega Trinidad (74), Bishop-Prelate emeritus of Juli (Peru) |
