- O
- OO
- OO
- OO
- OO
- OOak
- OakObe
- ObeObl
- OblOC
- OCOce
- OceOck
- OckOct
- OctOdd
- OddOde
- OdeODO
- odoOer
- OerOff
- OffOff
- OffOgi
- OgiOh
- OhOhh
- OhiOin
- OinOK
- OKokg
- okgOl
- OlOLB
- OlcOld
- OldOle
- OleOli
- OliOli
- OliOll
- OllOls
- OlsOma
- OmaOMC
- OmdOmi
- Omkon
- OnOnc
- OncOne
- OneOne
- OneOne
- OneOnh
- ONIOnl
- onl
- Oon
- OONOpe
- OpeOph
- OphOpt
- OptOra
- OraOrb
- ORBOrc
- OrcOrc
- OrcOre
- OreOrg
- OrgOri
- OriOri
- Oriorm
- OrnOrp
- OrpOrq
- OrqOrt
- OrtOsa
- OsaOsc
- OscOsk
- oskOss
- OssOT
- OtaOth
- Othott
- OTTOtt
- OttOur
- OurOut
- OutOut
- OutOut
- OutOva
- OvaOve
- OveOvi
- OviOwe
- OweOx
- OXOyi
- Ozi
- oziOZZ
- O'Connor, Tony (New Age composer)
- O'Day, Anita & Tjader, Cal
- O'Day, Anita with May, Billy
- O'Day, Anita with May, Billy & His Orchestra
- O'Day, Pat (pop/swing vocalist)
- O'Day, Teish
- O'Donis, Colby feat. Akon
- O'Donnell, Daniel & Duff, Mary
- O'Donnell, Kevin's, Quality Six
- O'Dowd, Erin
- O'Doyle Rules
- O'Flaherty, Jack (Jack Fla)
- O'funk'illo
- O'funk'illo y Tarque
- O'Hagan, Patrick (Irish tenor)
- O'Hara, Eureka
- O'Hara, Paige, Benson, Robby, Orbach, Jerry, Lansbury, Angela and Stiers, David Ogden
- O'Hara, Paige, White, Richard and Chorus
- O'Hearn, Patrick (American drummer and percussionist)
- 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'Leary, Jenny
- O'Malley, J. Pat
- O'Mara, Peter, Trio
- O'May, Pat (French musician)
- O'Meara, Keenan
- O'Mys, The
- O'Neal Twins, The
- O'Neal, Jamie
- O'Neal, Juliana
- O'Neil, Marykate
- O'Neill (Luis Ángel O'Neill Laureano, from Joan & O'Neill)
- O'Neill Brothers, The (Tim & Ryan)
- O'Neill, Chris
- O'Neill, Con
- O'Neill, David (Christian Trumpet Artist)
- O'Neill, Megan (Irish singer-songwriter)
- O'o (French pop duo (Victoria Suter & Mathieu Daubigné))
- O'Raspi, Apache
- O'Reilly, Jack
- O'Reilly, Lorkin
- O'Reilly, Noel (Active since 2019)
- O'Reilly, Ryan (the band)
- O's, The (Dallas bluegrass duo)
- O'Shea
- O'Shea
- O'Shea, Brendan
- O'Sullivan, Camille
- O'Sullivan, Eoghan
- O'Vaque, Ajax Ray
- O'Yaba
- O’, Gary (Canadian singer‐songwriter Gary O’Connor)
- O’2L
- O’Banion, John
- O’Beirne, Gerry (Irish guitarist)
- O’Bi, Cam & Laurence, Vivian
- O’Brian, Hugh
- O’Brien, Daniel (film score composer, notably his award winning "Colorado Suite")
- O’Brien, Dermot
- O’Brien, Ed (guitarist & songwriter in Radiohead)
- O’Brien, Hod
- O’Brien, Ian
- 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 & O'Brien, Mollie
- O’Brien, Tim & Scott, Darrell
- O’Brien, Tim and O’Boys, The
- O’Brien, Tim feat. Fabricius, Jan
- O’Brien, Virginia
- O’Bros (hip‐hop duo from Munich, Germany)
- 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
