Gaston IV, Count of Foix

Gaston IV, Count of Foix, Viscount of Béarn (27 November 1422 - 25 July/28 July 1472) was a French nobleman from Bearn, who founded a brief-ruling dynastic house of the Kingdom of Navarre.

He was a son of John I, Count of Foix and Jeanne d'Albret. His maternal grandparents were Charles d'Albret, Constable of France and co-commander of the French army, killed at the Battle of Agincourt, and his wife Marie de Sully.

Gaston married the Navarrese Infanta, Leonor, in 1436. Her parents were John II and Blanche I of Navarre. At the time, Leonor appeared to have few prospects: her father was a younger son and brother of the Kings of Aragon, and Leonor had a brother, Charles of Viana, and an older sister, Blanca, standing between herself and the inheritance of Navarre. However, family dissent and death eliminated both Charles and Blanca; Leonor's father usurped the Navarrese throne, to which he added in 1458 the throne of Aragon (his older brother having died without legitimate children), and, following the deaths of Charles and Blanca, promised the inheritance of Navarre to Leonor and her husband in return for their loyalty to him, which was given.

They had eight children:

• Gaston de Foix (1443-1470), (sometimes called “Gaston V of Foix”), Viscount of Castelbon, prince of Viana (1462-1470), lieutenant general of Navarre (1469).
• Jean de Foix (1446-1500), Viscount of Narbonne (1468-1500), count d' Étampes (1478-1500). He claimed the throne of Navarre upon the death of his nephew François Phébus. He married in 1476 Marie of Orleans (1457-1493)
• Margaret de Foix (1449-1486), married on June 27, 1471 at Clisson Francis II, Duke of Brittany. They were parents of Anne of Brittany, twice queen of France as consort to both Charles VIII of France and Louis XII of France.
• Pierre de Foix (February 7, 1449 to August 10, 1490), (sometimes called “Pierre II of Foix”), called Pierre the Young, cardinal (1576), viceroy of Navarre (1479-1484)
• Marie de Foix (c.1452-1467)
• Jeanne de Foix (c.1454-c.1476), married in August 1469 in Lectoure, to Jean V of Armagnac (1420-1473).
• Catherine de Foix (c.1460-before 1494), married in 1469 Gaston de Foix, Count of Candale (c.1440-1500), (sometimes called “Gaston II of Foix”).