Viscounts | Titles by Rank
- Viscounts of Noblet d' Anglure
- Viscounts of Nogueira da Gama
- Viscounts of Nogueiras
- Viscounts of Noronha
- Viscounts of Nossa Senhora da Luz
- Viscounts of Nossa Senhora das Mercês
- Viscounts of Nossa Senhora do Porto de Ave
- Viscounts of Nova Friburgo
- Viscounts of Nova Granada
- Viscounts of Nova Java
- Viscounts of Odivelas
- Viscounts of Oleiros
- Viscounts of Olinda
- Viscounts of Olivã
- Viscounts of Olivais
- Viscounts of Olival
- Viscounts of Oliveira
- Viscounts of Oliveira
- Viscounts of Oliveira
- Viscounts of Oliveira do Conde
- Viscounts of Oliveira do Douro
- Viscounts of Oliveira do Paço
- Viscounts of Oliveira Duarte
- Viscounts of Omelas
- Viscounts of Oña
- Viscounts of Orta
- Viscounts of Ottolini
- Viscounts of Ouchies
- Viscounts of Ouchy
- Viscounts of Ouguela
- Viscounts of Ourém
- Viscounts of Ouro Preto
- Viscounts of Outeiro
- Viscounts of Ovar
- Viscounts of Paço d' Arcos
- Viscounts of Paço de Lumiar
- Viscounts of Paço de Nespereira
- Viscounts of Paiva
- Viscounts of Paiva Manso
- Viscounts of Palma de Almeida
- Viscounts of Palmeira
- Viscounts of Palmeira
- Viscounts of Panat
- Viscounts of Paradinha do Outeiro
- Viscounts of Paraguaçú
- Viscounts of Paraíba
- Viscounts of Paraibúna
- Viscounts of Paraná
- Viscounts of Paranaguá
- Viscounts of Paredes