O-3
- Once Upon a Dead Man
- OnCue
- Onda Vaga
- ondaGranda
- Ondar
- Ondatrópica
- Ondina
- Ondra
- One 2 Ka 4
- One 4 One
- One Accord
- One Acen
- One Arm Away
- One Arm Train
- One Armed Man (The)
- One Bit
- One Block Radius
- One Call
- One Chance
- One Chance feat. Fabo
- One Dae
- One Day As A Lion
- One Desire
- One Direction
- One Dollar Short
- One Drop Forward
- One Eighty
- One Fine Day
- One From Many
- One Giant Leap
- One Hit Wonder
- One Hope Project
- One Hundred (The)
- One I Cinema
- One Jo
- One Jp (The)
- One KyNg PaC & The Only Topic
- One Last Look
- One Less Reason
- One Machine
- One Man And His Droid
- One Man Army
- One Mic
- One Mile Left
- One Million Berlin
- One Minute Silence
- One Minutes
- One More Day
- One More Time
- One Morning In Spring
- One Morning Left
- One Nation Crew
- One Night Only
- One Off The Pace
- One Ok Rock
- One Pound Fish Man
- One Republic
- One Republic feat. Timbaland
- One Ring Zero
- One Session
- One Shot
- One Sock Thief
- One Star Story
- One Step Too Many
- One Strike Left
- One T feat. Cool T
- One Take
- One thing remains
- One Trip
- One True Pairing
- One True Voice
- one twelve
- One Voice
- One Way
- One Way System
- One Way To Kansas
- One Week Notice
- One Without
- One World
- One Worship
- One Year Later
- One(8)Seven
- One-Eyed Doll
- One-T
- One-T and Cool-T
- One.Be.Lo
- One:Day:Life
- OneChot
- ONEFOUR
- Onegai Twins
- Oneida
- Onelight
- Oneohtrix Point Never
- ONER
- OneRepublic
- OneStarCity
- Onething Live
- ONEUS
- Onew (SHINee)
- ONEWE
- Onewerd
- OneWorld
- ONF
- Ong Seong Wu
- Ongoing Concept (The)
- ONHEL
- ONI
- Onicks
- Onion Brothers (The)
- Onirica
- Onita Boone
- Onitsha
- Onk Lou
- Onkel Hotte
- Onkel Tom
- Onkel Zwieback
- Onlap
- Online
- Online Euphoria
- Only
- only attitude counts
- Only Boys Aloud
- Only Case
- Only Children (The)
- Only Crime
- Only Girl
- Only Girls
- Only Innocent Die
- Only One Felipe
- Only Ones (The)
- Only Seven Left
- Only The Family
- Only The Poets
- Only The Young
- OnlyReal
- Onnix
- ONR
- Ontologia
- ONUKA
- Onur
- Onur Akin
- Onur Mete
- Onur San
- onwhenready
- Ony Martos
- Onya Gray
- Onyx
- Onyx Colony
- Onyx Creación Divina
- Onze
- Onze:20
- OOFT!
- Oohlas (The)
- Ookay
- Oomhp
- Oomp Camp
- Oomph
- Oomph!
- Oonagh
- ooops
- OOVEE & Flatdisk
- Oowee
- OP 2
- Op jot Kölsch
- Op zoek naar Nemo
- Opa
- Opa Tsupa
- Opa Unger
- Opanso je ljubiti
- Opérettes
- OPB
- Open (The)
- Open Air Stereo
- Open Hand
- Open Mike Eagle
- Open Minded
- Open the Nile
- Open The Skies
- Open Water
- Openfire
- Openside
- Opera - Ludwig Is Alive
- Opera De Nuit
- Operación Triunfo 2017
- Operación Triunfo 2018
- Operación Triunfo 2020
- operacion triunfo 1
- Operation
- Operation Ivy
- Operation M.D. (The)
- Operation Semtex
- Operator Please
- Opeth
- OPFuture
- Ophélie Cassy
- Ophélie Winter
- Ophelia
- Ophelias (The)
- Ophelya
- Ophidian
- Ophiocordyceps
- Opi The Hit Machine
- Opia
- Opiúm
- Opiium
- Opio
- Opium Baby
- Opiuo
- Oplus
- OPM
- Opodeldox
- Opossom
- Oppnox
- OppositE
- Opposite Sounds
- Optical 2
- Optik Army
- Optikhelden
- Optimale Härte
- Optimo
- Optimus
- Opus Aeterna
- Opus Dai
- Opuz
- Oques Grasses
- OR
- Ora Maté
- Oracle
- Oracle Sisters
- Oral Bee
- Oran 'Juice' Jones
- Orange And Lemon
- Orange Black
- Orange Grove
- Orange Skyline
- Oranus Lassus
- Oré
- Orba Squara
- Orbit Culture
- Orchestraccia
- Orchestral - The Party Has Just Begun
- Orchestral Manoeuvres In The Dark
- Orchestral Manoeuvres In The Dark (OMD)
- Orchestre Alan Record
- Orchestre Lamoureux
- Orchid
- Orchid Ablaze
- Ordarada
- Ordeal (The)
- Ordeal By Fire
