Former Owner
- Oliver Henry Perkins1
- Oliver R. Barrett2
- Otto Ege30
- Over, Watson1
- Paolo Gallo1
- Paolo Giovio1
- Paolo Vimercati Sozzi2
- Parroco di Taviano, Luigi Bruno, active 20th century1
- Patrick Brady1
- Paul Gottschalk1
- Paul Sabatier1
- Payne and Foss1
- Peter Christos1
- Peter Eaton1
- Peter Ludwig1
- Petrus Joseph Puccius1
- Petrus Leonardus1
- Petrus Martinotius1
- Petrus de Thureyo1
- Pettini Libraria di Antonio Pettini1