John III (French: Jean d'Albret) was jure uxoris King of Navarre from 1484 until his death, as husband and co-ruler of Queen Catherine. He was a son of Alain I of Albret, Lord of Albret, and his wife, Frances of Châtillon-Limoges.
He became King of Navarre and Count of Foix by virtue of his 1484 marriage to Queen Catherine (1470–1517), successor of her brother Francis Phoebus in 1483. He shared with Catherine tasks related to the government of the kingdom, but his rule was marked by the guardianship of Catherine's mother Magdalena de Valois up to 1494 (she died in 1495) and persistent diplomatic and military pressure of Ferdinand II of Aragon over the Crown of Navarre, supported on the ground by the Beaumont party of Navarre.
After the Aragonese king Ferdinand's death in January 1516, king John III mustered an army in Sauveterre-de-Béarn made up of Navarrese exiles and men from all over his domains, especially from Béarn, but the total figure of combatants amounted to no more than several hundred people. Their advance was stopped by the Castilians right on the Pyrénées due to spies informing Cardinal Cisneros. Depressed by the defeats and adverse diplomatic results, John III died at the castle of Esgouarrabaque in Monein, Béarn, on 14 June 1516. Queen Catherine outlived him only by a few months.