- O
- OO
- OO
- OO
- OOak
- OakObe
- ObeObr
- ObrOcc
- OccOce
- OceOct
- OctODD
- ODDODE
- ODEOdr
- OdrOfb
- OfdOff
- OffOgf
- OghOh
- OhOHN
- OHNOje
- OjeOka
- OKAOku
- OkuOla
- OlaOld
- OldOle
- OleOli
- OliOli
- OllOls
- OlsOm
- OmOme
- OmeOMO
- OmoOnc
- OncOne
- OneOne
- OneOne
- OneONL
- ONLOnr
- OnrOol
- OolOpe
- OpeOpi
- OpiOqu
- OquOra
- OraOrb
- Orborc
- orcOre
- OREOri
- OriOri
- OriOrl
- ORMOrp
- OrpOrr
- Ors
- OrvOsb
- OsbOse
- OseOsm
- OsmOsu
- OsuOth
- OthOtt
- OttOua
- OuaOur
- OurOut
- OutOut
- OutOva
- Ovaove
- oveOVT
- OvvOwl
- OwlOxm
- Oxm
- ozz
- O'Hooley & Tidow
- O'Kane, Damien (Northern Irish folk musician)
- O'Kane, John
- O'Keefe, Laurence (British bassist of Jazz Butcher, Levitation & Dark Star)
- O'KOYE (Korean hip-hop duo)
- O'Leary, Jenny
- O'Malley, J. Pat
- O'Malley, Lenore
- O'Mara, Peter, Trio
- O'May, Pat (French musician)
- O'Meara, Keenan
- O'Montis, Paul
- O'Neal Twins, The
- O'Neal, Jamie
- O'Neal, Juliana
- O'Neill (Luis Ángel O'Neill Laureano, from Joan & O'Neill)
- O'Neill Brothers, The (Tim & Ryan)
- O'Neill, Con
- O'Neill, David (Christian Trumpet Artist)
- O'Neill, Harper
- O'Neill, Megan (Irish singer-songwriter)
- O'o (French pop duo (Victoria Suter & Mathieu Daubigné))
- O'Reilly, Lorkin
- O'Reilly, Noel (Active since 2019)
- O'Reilly, Ryan (the band)
- O'Ryan (Irish Musician)
- O's, The (Dallas bluegrass duo)
- O'Shea
- O'Shea, Brendan
- O'Sullivan, Camille
- O'Sullivan, Eoghan
- O'Yaba
- O’, Gary (Canadian singer‐songwriter Gary O’Connor)
- O’2L
- 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 & 24kGoldn
- O’Brien, Olivia feat. FLETCHER
- O’Brien, Olivia ft. blackbear
- O’Brien, Olivia ft. G‐Eazy & Love, Drew
- O’Brien, Paul, All Stars Band, The
- 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 and O’Boys, The
- 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. Aly & Fila
- 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. Lo-Fi Sugar
- O’Callaghan, John Feat. Ria
- O’Callaghan, John feat. Ria
- O’Callaghan, John featuring Ria
- O’Connell, Helen
- O’Connell, Helen & Dorsey, Jimmy and Orchestra, His
- 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, Cavan
