Culture magazines
- O'Neill, William L.
- O'Regan, Valerie R.
- O'Reilly, Kenneth
- O'Reilly, Victor
- O'Rourke, James S., IV
- O'Rourke, Michael
- O'Rourke, P. J.
- O'Rourke, William
- O'Shaughnessy, Ellen Cassels
- O'Shea, Kathleen A.
- O'Shea, Pat (Shiels)
- O'Siadhail, Micheal
- O'Sullivan, Vincent (Gerard)
- O'Toole, Fintan
- O'Toole, Judith Hansen
- O'Toole, Lawrence
- O.C. and Stiggs
- O.H.M.S.
- O.S.S.
- Oakes, Elizabeth H.