- O'Brian, Terrie
- O'Brien, Gerry
- O'Brien, Sean
- O'Byrne, Nicola
- O'Byrne, Nicola
- O'Callaghan, Jonathan
- O'Connell, Joanne
- O'Connor, Bridget
- O'Connor, Des
- O'Connor, Elizabeth
- O'Donnell, Bridget
- O'Dowd, Chris
- O'Furniture, Patty
- O'Hara, Lauren
- O'Hara, Mo
- O'Hara, Natalia
- O'Hare, Gráinne
- O'Kane, Owen
- O'Malley, Rory
- O'Neill, Amanda
- O'Neill, Heather Aimee
- O'Neill, Martin
- O'Reilly, Bill
- O'Rourke, P. J.
- O'Shaughnessy, Patrick
- O'Sullivan, Feargus
- O'Sullivan, Heather
- O'Sullivan, Ronnie
- O'Sullivan, Suzanne
- O'Toole, Peter
- O'Yeah , Zac
- Oakley, Phil
- Oakley, Stu
- Obama, Michelle
- Obiora, Michael
- Oborne, Martine
- Ochlan, PJ
- Ochman, Joe
- Ochota, Mary-Ann
- Odo
- Ogilvie, Sara
- Ojari, Daniel
- Ojo, Adenrele
- Okello, Kate
- Okoye, Nneka
- Okuboyejo, Sandra
- Olav Lahlum, Hans
- Oldbury, Stephen
- Oldfield, Richard
- Oldham, Andrew
- Oliver, Abi
- Oliver, Jana
- Olivotti, Sergio
- Olley, Darcie
- Olson, Parmy
- Olukoya, Dami
- Olusoga, David
- Olusoga, Kemi
- Olusoga, Yinka
- Onayemi, Prentice
- Ondaatje, Michael
- Ono, Yoko
- Onwukwe, Ben
- Orczy, Baroness
- Ord, Charlotte
- Orlando, Jade
- Orsini, Kate
- Ortega, Julio
- Orwell, George
- Osborne, George
- Osbourne, Jack
- Oseid, Kelsey
- Osman, Jim
- Osmond, Nicholas
- Osmond, Richard
- Osorio, Lee
- Ostaseski, Frank
- Ounsley, Jodie
- Ovens, Sarah
- Owen, Amanda
- Owen, Sid
- Owens, Lisa
- Owusu, Jude
- Oxlade, Chris
- Oyemakinde, Tomi
- Oyer, Paul
- Oyeyemi, Helen
- Ozolins, Janis
- O’Connor, Katherine Tiernan
- O’Neill, Eamonn