Juan Vélaz de Medrano IV was the royal Chamberlain for King Charles III of Navarre in 1414 and King John II of Aragon and Navarre in 1432. Juan was a noble and knight from the Kingdom of Navarre. He was the lord of Igúzquiza, Arguiñano, Arzoz, Learza, Artazu, Zabal, Orendáin, and the alcaide of Monjardín Castle and Viana. He is the son of the ricohombre Don Alvar Diaz de Medrano y Almoravid. Don Juan Vélaz de Medrano was active in the Hundred Years' War during the war of Languedoc (1412), the civil war in Aragon (1412) and successfully defended Viana against the Kingdom of Castile in 1429–1430. In 1410, Don Juan Vélaz de Medrano was targeted in a rebellion from his fiefdom of Orendáin. His grandsons Juan and Jaime Vélaz de Medrano y Echauz were leaders in the defense against the conquest of Navarre, particularly in 1512 and 1522.

Jaime Vélaz de Medrano y Echauz was a noble from the House of Medrano in the independent Kingdom of Navarre. He was a knight of Navarre, a royal guard of the king, captain of the kings standing army, alcaide and mayor of Amaiur-Maya and one of the leading defenders of the Navarrese crown against the Spanish conquest of Iberian Navarre. Jaime Vélaz de Medrano is believed to have served as the alcaide of Maya Castle from 2 October 1521, to 19 July 1522.