Princes | Titles by Rank
- Princes of Oliveto
- Princes of Oneglia
- Princes of Oneglia
- Princes of Orange
- Princes of Orange-B
- Princes of Orange-C
- Princes of Orange-H
- Princes of Orange-Nassau
- Princes of Oranje
- Princes of Oriolo
- Princes of Orléans
- Princes of Orleans and Braganza
- Princes of Orsini und Rosenberg
- Princes of Ottaiano
- Princes of Ottajano
- Princes of Paceco
- Princes of Palagonia
- Princes of Palazzo San Gervasio
- Princes of Palermo
- Princes of Palestrina
- Princes of Paliano
- Princes of Palizzi
- Princes of Panagjury
- Princes of Pandolfina
- Princes of Parma
- Princes of Paternò
- Princes of Paz
- Princes of Peresopnitsa
- Princes of Pereyaslav
- Princes of Pérsia
- Princes of Pesaro
- Princes of Pescara
- Princes of Petraprecia
- Princes of Pettorano
- Princes of Pfalzburg
- Princes of Phalsbourg
- Princes of Piacenza
- Princes of Piedimonte
- Princes of Piemonte
- Princes of Pietralcina
- Princes of Pietrapersia
- Princes of Piombino
- Princes of Piscielli de la Cruz Haedo
- Princes of Pless
- Princes of Poggio-Suasa
- Princes of Poggioreale
- Princes of Poix
- Princes of Polignac
- Princes of Polizzi
- Princes of Polónia