Illustrators
- Eilis O'Connell 1
- Pixie O'Harris 1
- Hugh O'Neill 2
- John P. O'Neill 1
- Tom O'Reilly 1
- H. Oakes-Jones 1
- G. Oakley 1
- Graham Oakley 9
- Y. Oda 1
- Alice M. Odgers 1
- Alan Odle 1
- Angela Ogden 3
- Carol Ogilvie 3
- James S. Ogilvy 1
- Ogle 6
- Richard Ogle 1
- Richard B. Ogle 1
- Jose G. Ojados 1
- Frank Oldham 1
- Olinda 1
- Tony Oliver 1
- Clara Olmstead 1
- Lola Onslow 2
- Olive F. Openshaw 5
- Winfried Opgenoorth 1
- E.R. Ord 1
- Giulia Orecchia 2
- Chris Orgill 1
- Jan Ormerod 3
- Jack Orr 5
- Monro S. Orr 1
- Stewart Orr 6
- Robert Osborn 1
- D. Osborne 2
- Rex Osborne 1
- Edward Osmond 2
- B. Ostertag 1
- Paul Ott 1
- J.B. Oudry 1
- R.F. Outcault 4
- Ida Rentoul Outhwaite 7
- W.H. Overend 4
- T.J. Overnell 1
- Ivan Owen 1
- Juliette A. Owen 1
- W. Owen 1
- Will Owen 1
- Gail Owens 1
- Marjorie Owens 2
- Helen Oxenbury 9