Duke of Frías is a hereditary title created in 1492 by King Ferdinand II of Aragon

Ferdinand II of Aragon

Ferdinand the Catholic was King of Aragon , Sicily , Naples , Valencia, Sardinia, and Navarre, Count of Barcelona, jure uxoris King of Castile and then regent of that country also from 1508 to his death, in the name of...

. It became one of the most important titles in Spain.

The House of Velasco was one of the most powerful and influential noble Castilian families of the Middle Ages and the beginning of the Modern Era. Its original territories were situated around Burgos

Burgos

Burgos is a city of northern Spain, historic capital of Castile. It is situated at the edge of the central plateau, with about 178,966 inhabitants in the city proper and another 20,000 in its suburbs. It is the capital of the province of Burgos, in the autonomous community of Castile and León...

, Álava

Álava

Álava is a province of Spain and a historical territory of the Basque Country, heir of the ancient Lord of Álava. Its capital city is Vitoria-Gasteiz which is also the capital of the autonomous community...

 and eastern Cantabria

Cantabria

Cantabria is a Spanish historical region and autonomous community with Santander as its capital city. It is bordered on the east by the Basque Autonomous Community , on the south by Castile and León , on the west by the Principality of Asturias, and on the north by the Cantabrian Sea.Cantabria...

. The founder of this lineage was Juan de Velasco (1368–1418), Lord High Chamberlain-Chancellor Camarero mayor to the kings of Castile. His elder son, Pedro Fernández de Velasco, became the first count of Haro.

When the first count died in the 1470s, he was succeeded by his eldest son Pedro Fernández de Velasco, 2nd Count of Haro. Pedro Fernández de Velasco became the hereditary constable of Castile

Constable of Castile

Constable of Castile was a title created by John I, King of Castile in 1382, to substitute the title Alférez Mayor del Reino. The constable was the second person in power in the kingdom, after the King, and his responsibility was to command the military in the absence of the ruler.In 1473 Henry IV...

, a title which previously had been only a life appointment. His son, Don Bernardino de Velasco, third Count of Haro and second hereditary constable of Castile, received the title of duke of Frías.

Counts and countesses of Haro

1. Don Pedro Fernández de Velasco, 1st Count of Haro
2. Don Pedro Fernández de Velasco, 2nd Count of Haro (1430–1492)

Dukes and duchesses of Frías

1. Don Bernardino Fernández de Velasco, 1st Duke of Frías
   Bernardino Fernández de Velasco, 1st Duke of Frías
   Bernardino Fernández de Velasco, 1st Duke of Frías, Grandee of Spain was a Spanish nobleman and military figure of the last stages of the Reconquista....
   
    (c.1450 - 9 February 1512)
2. Don Íñigo Fernández de Velasco, 2nd Duke of Frías
   Íñigo Fernández de Velasco, 2nd Duke of Frías
   Íñigo Fernández de Velasco, 2nd Duke of Frías, Grandee of Spain, ), was a Spanish nobleman and Duke of Frias....
   
    (c.1460 - 15 December 1528)
3. Don Pedro Fernández de Velasco, 3rd Duke of Frías
   Pedro Fernández de Velasco, 3rd Duke of Frías
   Pedro Fernández de Velasco, 3rd Duke of Frías , Grandee of Spain was a Spanish nobleman.Fernández de Velasco was the son of Íñigo Fernández de Velasco, 2nd Duke of Frías and of María de Tovar, Lady of Berlanga...
   
    (c.1485)
4. Don Íñigo Fernández de Velasco, 4th Duke of Frías
   Íñigo Fernández de Velasco, 4th Duke of Frías
   Íñigo Fernández de Velasco, 4th Duke of Frías, Grandee of Spain, , , was a Spanish nobleman.Fernández de Velasco was the son of Juan Sancho de Tovar, 1st Marquis of Berlanga and of María Girón, Lady of Gandul and Marchenilla...
   
    (c.1530 - 1585)
5. Don Juan Fernández de Velasco, 5th Duke of Frías
   Juan Fernández de Velasco, 5th Duke of Frias
   Juan Fernández de Velasco, 5th Duke of Frías was a Spanish nobleman and diplomat.Juan Fernández de Velasco was the son of Íñigo Fernández de Velasco; and of Maria Angela de Aragón y Guzmán El Bueno. He inherited his father's title of Constable of Castile, and was present at the signing of the...
   
    (c.1550 - 15 March 1613)
6. Don Bernardino Fernández de Velasco, 6th Duke of Frías
   Bernardino Fernández de Velasco, 6th Duke of Frias
   Bernardino Fernández de Velasco, 6th Duke of Frias, Grandee of Spain, , was a Spanish nobleman and diplomat.-Biography:...
   
    (c.1610 - 1652)
7. Don Íñigo Melchor de Velasco, 7th Duke of Frías
   Íñigo Melchor de Velasco, 7th Duke of Frias
   Íñigo Melchor de Velasco, 7th Duke of Frías, Grandee of Spain, , was a Spanish nobleman and Governor-General of the Spanish Netherlands.-Biography:...
   
    (c.1635 - 27 September 1696)
8. Don José Fernández de Velasco, 8th Duke of Frías (c.1660 - 9 January 1713)
9. Doña María de Velasco, 9th Duchess of Frías
10. Don Agustín Fernández de Velasco, 10th Duke de Frías
11. Don Bernardino Fernández de Velasco, 11th Duke of Frías
12. Don Martín Fernández de Velasco, 12th Duke of Frías
13. Don Diego Fernández de Velasco, 13th Duke of Frías (1754–1811)
14. Don Bernardino Fernández de Velasco, 14th Duke of Frías
    Bernardino Fernández de Velasco, 14th Duke of Frías
    Don Bernardino Fernández de Velasco-Pacheco y Benavides, 14th Duke of Frías, Grandee of Spain, KOGF was a Spanish noble, politician, diplomat and writer who served in 1838 as Prime Minister of Spain...
    
    
15. Don José María Fernández de Velasco, 15th Duke of Frías
16. Don Bernardino Fernández de Velasco, 16th Duke of Frías
17. Don Guillermo Fernández de Velasco, 17th Duke of Frías
18. Don José María Fernández de Velasco, 18th Duke of Frías
19. Don Francisco de Borja de Soto, 19th Duke of Frías

Sources