The hereditary Spanish title Duke of Frías was created in 1492 by Ferdinand II of Aragon. It became one of the most important titles amongst the Grandees of Spain.
The House of Velasco was one of the most powerful and influential noble Castilian families of the Middle Ages and beginning of the Modern Era. It's original territories were situated around Burgos, Álava and eastern Cantabria.
The founder of this lineage was Juan de Velasco (1368-1418), camarero mayor to the Kings of Castile. His elder son, Pedro Fernández de Velasco, became the first Count of Haro. When he died in the 1470s he was succeeded by his eldest son, Pedro .
Pedro Fernández III de Velasco (1430 - 1492), the second Count of Haro, became the Constable of Castile, a title which his heirs would then retain. His son, Don Bernardino de Velasco, third Count of Haro and second Constable of Castile, received the title of Duke of Frías.
Dukes of Frías
- Bernardino de Velasco, 1st Duke of Frias (c. 1450 - 09.02.1512)
- Iñigo Fernandez de Velasco, 2nd Duke of Frias (c. 1460 - 15.12.1528), his brother
- Pedro Fernández de Velasco, 3rd Duke of Frias (c. 1485), his son
- Iñigo Fernandez de Velasco, 4th Duke of Frias (c. 1530 - 1585), his nephew
- Juan Fernández de Velasco, 5th Duke of Frias (c. 1550 - 15.03.1613), his son
- Bernardino Fernández de Velasco, 6th Duke of Frias (c. 1610 - 1652), his son
- Íñigo Melchor de Velasco, 7th Duke of Frias (c. 1635 - 27.09.1696), his son
- José Fernández de Velasco y Tovar, 8th Duke of Frias (c. 1660 - 09.01.1713), his nephew
- María de Velasco y Benavides, 9th Duchess of Frías.
- Agustín Fernández de Velasco y Bracamonte, 10th Duke de Frías
- Diego Fernández de Velasco, 13th Duke of Frías and Uceda, Count of Alba and Lista (1754 - 1811)
