Educational magazines
- O'Hagan, Andrew 1968–
- O'Hagan, Christine
- O'Hanlon, Ellis (Ingrid Black, a joint pseudonym)
- O'Hanlon, Michael E.
- O'Hara, Phillip Anthony 1954-
- O'Hare, Brian
- O'Hearn, Denis 1953-
- O'Hehir, Diana 1929- (Diana F. O'Hehir)
- O'Hehir, Diana 1929–
- O'Higgins, Paul 1927-2008
- O'Kane, Bernard
- O'keefe, Deborah (Janney) 1939-
- O'Keefe, Kevin
- O'Keefe, Susan Heyboer
- O'Keefe, Susan Heyboer
- O'Keeffe, (Peter) Laurence 1931-2003
- O'Keeffe, Patrick 1963–
- O'Leary, Denyse 1950-
- O'Leary, Don 1955-
- O'Leary, Kevin