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- Berry Oakley (The Allman Brothers Band)
- Marty O'Brien (We Are the Fallen)
- Brian "Big Hands" O'Conner (Eagles of Death Metal)
- Shavo Odadjian (System of a Down)
- Bernard Odum (James Brown)
- Tetsuya Ogawa (L'Arc-en-Ciel, Tetsu69)
- Patrick O'Hearn (Frank Zappa)
- Mike Oldfield
- Nick Oliveri (Kyuss, The Dwarves, Mondo Generator, Queens of the Stone Age)
- Stefan Olsdal (Placebo)
- Peter Olsson (Europe)
- Nick O'Malley (Arctic Monkeys)
- Jerry Only (The Misfits)
- Cait O'Riordan (The Pogues)
- Benjamin Orr (The Cars)
- Jackie Orszaczky
- Joe Osborn
- Franc O'Shea
- Mat Osman (Suede)
- Mark Owen (Take That)
- Scott Owen (The Living End)
Read more about this topic: List Of Bass Guitarists