Dukes | Titles by Rank
- Dukes of Spadafora
- Dukes of Spezzano
- Dukes of Spoleto
- Dukes of Spoletto
- Dukes of Squillache
- Dukes of Srem
- Dukes of St-Save
- Dukes of Staritsa
- Dukes of Stiria
- Dukes of Suábia
- Dukes of Suárez
- Dukes of Sueca
- Dukes of Suffolk
- Dukes of Suffolk-I
- Dukes of Suffolk-II
- Dukes of Sully
- Dukes of Sulzbach
- Dukes of Surrey
- Dukes of Sussex
- Dukes of Sussex-II
- Dukes of Sutherland
- Dukes of Syrmia
- Dukes of T'Serclaes
- Dukes of Talavera de la Reina
- Dukes of Talleyrand
- Dukes of Tamames
- Dukes of Tancos
- Dukes of Tarancón
- Dukes of Tarifa
- Dukes of Taron
- Dukes of Taurisano
- Dukes of Teck
- Dukes of Teramo
- Dukes of Terceira
- Dukes of Termoli
- Dukes of Termoli
- Dukes of Termoli
- Dukes of Terranova
- Dukes of Terranova
- Dukes of Tervuren
- Dukes of Teschen
- Dukes of Tessalónica
- Dukes of Tetuán
- Dukes of the Angrian Saxons
- Dukes of the Austrasianos
- Dukes of Thouars
- Dukes of Tingry
- Dukes of Tocco
- Dukes of toda a Sérvia
- Dukes of Tolve