- Pelagianism1
- Penance (Canon law)1
- Persephone (Greek deity)1
- Personal narratives1
- Pesciori, Guglielmo1
- Phalaris, Tyrant of Agrigentum, active 6th century B.C.1
- Pharmacognosy1
- Pharmacology1
- Pharmacy1
- Philip III, King of Spain, 1578-16211
- Piccolomini, Alessandro1
- Piccolomini, Andreas1
- Piccolomini, Antonio Maria d'Enea1
- Piccolomini, Giacomo d'Antonio Maria d'Enea1
- Piccolomini, Giovanni d'Andrea di Nanni Todeschini, 1475-15371
- Pilgrims and pilgrimages1
- Pistus, Augustus1
- Pius IV, Pope, 1499-15651
- Pius V, Pope, 1504-15721
- Plague1