Illustrators
- Michael O'Clery 1
- Hugh O'Neill 2
- Tom O'Reilly 5
- Paul O'Shea 1
- Graham Oakley 1
- Angela Ogden 2
- H.A. Ogden 1
- John Ogilby 1
- Carol Ogilvie 1
- Sara Ogilvie 2
- James S. Ogilvy 1
- Ogle 5
- Richard B. Ogle 1
- Jose G. Ojados 1
- Olinda 1
- Tony Oliver 1
- Clara Olmstead 1
- Lola Onslow 1
- Olive F. Openshaw 25
- F. Opper 1
- Giulia Orecchia 2
- Jan Ormerod 5
- Jean-Paul Orpinas 1
- Jack Orr 4
- Monro S. Orr 1
- Stewart Orr 5
- Robert Osborn 1
- D. Osborne 1
- Rex Osborne 1
- Edward Osmond 1
- B. Ostertag 1
- Paul Ott 1
- J.B. Oudry 1
- R.F. Outcault 4
- Ida Rentoul Outhwaite 13
- Michal Ovcacik 1
- W.H. Overend 3
- T.J. Overnell 2
- H.J. Owen 1
- Ivan Owen 1
- W. Owen 1
- Will Owen 2
- Gail Owens 1
- Marjorie Owens 2
- Helen Oxenbury 9
- Oxley 1