- O
- OO
- OO
- OOak
- OakObe
- ObeObs
- ObsOce
- OceOCT
- OctOda
- OdaODE
- ODEODU
- ODUOfe
- OfeOG
- OGOh
- OhOhl
- OhmOjo
- Ojookg
- okhOla
- OlaOld
- OldOle
- OleOli
- OliOlm
- OLMOma
- OmaOme
- OmeOmo
- OMPOnd
- OndOne
- Oneone
- oneONJ
- OnkOns
- Ons
- OosOpe
- OpeOpu
- OpuOra
- OraOrc
- OrcOre
- OreOri
- OriOri
- OriOro
- OroOrq
- OrqOrv
- OrvOsb
- OsbOsk
- OskOst
- Oth
- OthOtt
- OttOur
- OurOut
- OutOut
- OutOva
- OvaOve
- OveOwe
- OweOxf
- Oxf
- OZZ
- O’Banion, John
- O’Beirne, Gerry (Irish guitarist)
- O’Brien, Dermot
- O’Brien, Hod
- O’Brien, Kevin James
- O’Brien, Kyle
- O’Brien, Olivia
- O’Brien, Olivia feat. FLETCHER
- O’Brien, Richard
- O’Brien, Soledad (American broadcast journalist)
- O’Brien, Sonny (Belgian 2000s pop singer)
- O’Brien, Tim (US bluegrass musician)
- O’Brien, Tim & Scott, Darrell
- O’Brien, Tim feat. Fabricius, Jan
- O’Brother
- O’Bryan
- O’Byrne, Lucy (Soprano)
- O’Callaghan, John (trance DJ/producer/artist)
- O’Callaghan, John & Gallagher, Audrey
- O’Callaghan, John & Gallagher, Kathryn
- O’Callaghan, John & Howells, Sarah
- O’Callaghan, John & Kearney, Bryan
- O’Callaghan, John & Larkin, Betsie
- O’Callaghan, John & McLaughlin, Deirdre
- O’Callaghan, John & Stagg, Clare
- O’Callaghan, John feat. Gallagher, Audrey
- O’Callaghan, John feat. Gallagher, Audrey
- O’Callaghan, John feat. Gallagher, Kathryn
- O’Callaghan, John feat. Howells, Sarah
- O’Callaghan, John Feat. Howells, Sarah
- O’Callaghan, John feat. Jaren
- O’Callaghan, John feat. Jaren
- O’Callaghan, John Feat. Josie
- O’Callaghan, John feat. Josie
- O’Callaghan, John feat. Larkin, Betsie
- O’Callaghan, John Feat. Lo-Fi Sugar
- O’Callaghan, John feat. Lo-Fi Sugar
- O’Callaghan, John Feat. Ria
- O’Callaghan, John feat. Ria
- O’Callaghan, John featuring Ria
- O’Connell, Helen
- O’Connell, Lauren
- O’Connell, Maura
- O’Connell, Robbie
- O’Connor (Argentine hard rock band)
- O’Connor, Caroline
- O’Connor, Caroline & Bolton, John
- O’Connor, Des (English singer, lyricist)
- O’Connor, Donald
- O’Connor, Jennifer
- O’Connor, Mark (US bluegrass, country and classical fiddler/composer)
- O’Connor, Maz
- O’Connor, Paddy
- O’Connor, Sinéad (Irish singer-songwriter)
- O’Connor, Sinéad feat. Blockheads, The
- O’Connor, Sinéad feat. U2
- O’Day, Alan
- O’Day, Anita
- O’Day, Anita & Krupa, Gene
- O’Day, Anita & Three Sounds, The
- O’Day, Anita & Tjader, Cal
- O’Day, Anita with May, Billy
- O’Day, Molly (American country music vocalist)
- O’Death
- O’Dell, Kenny
- O’Dette, Paul (American conductor and lute player specialising in early music)
- O’Donis, Colby
- O’Donis, Colby feat. Akon
- O’Donis, Colby feat. Romeo
- O’Donis, Colby feat. T‐Pain
- O’Donis, Colby feat. Wall, Paul
- O’Donnell, Daniel
- O’Donnell, Daniel & Duff, Mary
- O’Donnell, Daniel with Billie Barry Kids, The
- O’Donnell, Daniel with Rathdowney Choir & Presentation Secondary School Choir, The
- O’Donnell, Erin
- O’Donnell, Martin
- O’Donnell, Martin & Salvatori, Michael
- O’Donnell, Martin & Salvatori, Michael
- O’Donnell, Martin and Salvatori, Michael
- O’Donnell, Rosie
- O’Donnell, Ryan & Rachel
- O’Donoghue, Cian
- O’Donovan, Aoife
- O’Donovan, Aoife feat. Cunningham, Madison
- O’Donovan, Aoife feat. Mitchell, Anaïs
- O’Donovan, Aoife feat. Russell, Allison
- O’Dowda, David
- O’Dwyer, Áine
- O’Farrill, Chico
