John II (June 29, 1397 – January 20, 1479) was a King of Aragon (1458 - 1479) and a King of Navarre (1425 - 1479). He was the son of Ferdinand I and his wife Eleanor of Albuquerque . John is regarded as one of the most stirring and most unscrupulous kings of the 15th century.

In his youth he was one of the infantes (princes) of Aragon who took part in the dissensions of Castile during the minority and reign of John II. Till middle life he was also lieutenant-general in Aragon for his brother and predecessor Alfonso V, whose reign was mainly spent in Italy. In his old age he was engaged in incessant conflicts with his Aragonese and Catalan subjects, with Louis XI of France, and in preparing the way for the marriage of his son Ferdinand with Isabella of Castile which brought about the union of the crowns. His trouble with his subjects were closely connected with the tragic dissension in his own family.

John was first married to Blanche of Navarre of the house of Evreux. By right of Blanche he became king of Navarre, and on her death in 1441 he was left in possession of the kingdom for his life. But a son Charles, called, as heir of Navarre, prince of Viana, had been born of the marriage. John from the first regarded his son with jealousy, which after his second marriage with Joan Henriquez, and under her influence, grew into absolute hatred. He endeavoured to deprive his son of his constitutional right to act as lieutenant-general of Aragon during his father's absence. The cause of the son was taken up by the Aragonese, and the king's attempt to join his second wife in the lieutenant-generalship was set aside.

There followed a long conflict, with alternations of success and defeat, which was not terminated till the death of the prince of Viana, perhaps by poison given him by his stepmother, in 1461. The Catalans, who had adopted the cause of Charles and who had grievances of heir own, called in a succession of foreign pretenders. In conflict with these the last years of King John were spent. He was forced to pawn Rousillon, his possession on the north-east of the Pyrenees, to Louis XI, who refused to part with it.

In his old age he was blinded by cataract, but recovered his eyesight by the operation of couching conducted by his physician Abiathar Crescas, a Jew. The Catalan revolt was pacified in 1472, but John had war, in which he was generally unfortunate, with his neighbour the French king till his death in 1479. He was succeeded by Ferdinand, his son by his second marriage, who was already associated with his wife Isabella as joint sovereign of Castile.

For the history, see Rivadeneyra, "Cronicas de los reyes de Castilla," Biblioteca de autores espanoles, vols. Ixvi, Ixviii (Madrid, 1845, &c.); G Zurita, Anales de Aragon (Saragossa, 1610). The reign of John II of Aragon is largely dealt with in WH Prescott's History of the Reign of Ferdinand and Isabella (1854).