Former Owner
- Omaha Public Library1
- Oric Bates2
- Orlandus de Fatiis1
- Oswald Carl Friedrich von Seilern und Aspang2
- Otto Ege90
- Otto Haas1
- Otto Jahn1
- Otto Orren Fisher1
- Otto Vollbehr3
- Owen D. Young1
- P. Desq1
- P. J. De Mat1
- P. Pigeot1
- PBA Galleries1
- Pandit Gobindpurshad1
- Pangracius Chrewczer1
- Paolo Gallo1
- Paolo Giovio4
- Paolo Guerrini1
- Paolo Vimercati Sozzi2