Dukes | Titles by Rank
- Dukes of Mormart
- Dukes of Morny
- Dukes of Mortemart
- Dukes of Moscovo
- Dukes of Mouchy
- Dukes of Muchran
- Dukes of Muchrani
- Dukes of Mukhrani
- Dukes of Munkacs
- Dukes of Munster
- Dukes of Münsterberg
- Dukes of Nájera
- Dukes of Nápoles
- Dukes of Nardò
- Dukes of Nassau
- Dukes of Nassau-Usingen
- Dukes of Nemi-E
- Dukes of Nemi-I
- Dukes of Nemours
- Dukes of Neopatras
- Dukes of Nepi
- Dukes of Nerike
- Dukes of Neuburg
- Dukes of Nevers
- Dukes of Newcastle
- Dukes of Newcastle-under-Lyme
- Dukes of Newcastle-upon-Tyne
- Dukes of Newcastle-upon-Tyne-II
- Dukes of Noailles
- Dukes of Noblejas
- Dukes of Nocera
- Dukes of Nochera
- Dukes of Noci
- Dukes of Noia
- Dukes of Noirmoutier
- Dukes of Nola
- Dukes of Norfolk-I
- Dukes of Norfolk-II
- Dukes of Norfolk-III
- Dukes of Normandy
- Dukes of Northumberland
- Dukes of Northumberland-I
- Dukes of Northumberland-II
- Dukes of Norwich
- Dukes of Noto
- Dukes of Ognano
- Dukes of Oldenburg
- Dukes of Olivares
- Dukes of Onano
- Dukes of Oporto