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- Oak Ridge Boys (1985)
- Oasis (2005)
- Maura O'Connell (1992)
- The O'Kanes (1988)
- Oklahoma City Philharmonic (1996)
- Okkervil River (2009)
- Old 97's (1998)
- Old Crow Medicine Show (2007)
- David Olney and the X-Rays (1982)
- Omar & the Howlers (1987)
- Roy Orbison (1983, 1997 "Legends" classic encore)
- Rick Orozco (1995)
- Joan Osborne (2001)
- K. T. Oslin (1989, 1992)
- Peter Ostroushko (1987 with Chet Atkins)
- Buck Owens (1989, 1997 "Legends" classic encore)
- Ozomatli (2004)
Read more about this topic: List Of Austin City Limits Performers