Henry of Castile (Italian: Arrigo di Castiglia) (March 1230 – August 1304), called El Senador (the Senator), was a Castilian infante, the younger son of Ferdinand III, King of Castile, by his first wife, Elisabeth of Hohenstaufen.
After his father's death in 1252, Henry and his brother Frederick chafed under the rule of their elder brother, King Alfonso. He also schemed with his stepmother, Joan of Ponthieu, who was accused of being his mistress. Henry started a rebellion in the southwest in October 1255; despite an initial victory over troops of the royal party, he was defeated near Morón, Spain and forced to flee the country. Henry sought refuge with his stepmother Joan in Ponthieu; she may have suggested he visit his sister Eleanor, who was married to Edward, the son and heir of King Henry III of England.
Henry arrived at the English court in August 1256. He lived comfortably there for three years entirely on King Henry's good graces until diplomatic relations with Castile eroded and Henry had to ask him to leave. Leaving in July 1259 for Valencia and Calatayud, where he asked the Infanta Constance of Aragon for marriage, as is stated in "El Libro de las Armas" by Juan Manuel, his nephew. The king of Aragon allowed the marriage only after Henry had conquered the moorish Kingdom of Niebla. Alfonso X of Castile and his wife Violente of Aragon opposed the marriage, and changed Henry for Infante Manuel, who finally married Constance. Henry, in revenge for the failed marriage and the loss of his kingdom of Niebla to his brother Alfonso, charged with a small army of knights through Castile and Extremadura sacking the country, and then left for Africa from Cadiz in 1260. Enrique became a mercenary in Tunis under the rule of Al Mustansir, where he would soon be joined by his brother Frederick. He later made his way to Italy, where he joined his cousin Charles of Anjou's campaign in 1266 to become King of Sicily (Battle of Benevento) and lent him large sums of money. It was here that Henry earned his title of El Senador when Charles had him made Senator of Rome. However, he was never repaid by Charles; and Henry had aspired to the kingship of Sardinia or some other high title, and found the senatorship poor compensation. As a result, when his cousin Conradin invaded Italy in 1268, Henry changed sides and joined him. He was one of Conradin's generals at the Battle of Tagliacozzo; he was in command of a host of three hundred Spanish knights sent by his brother Afonso X of Castille. He won the first encounter against the French, but was defeated by a surprise attack of a hidden reinforcement of one thousand French knights under Charles of Anjou. After the loss of the battle, he fled to the Convent of San Salvatore, Monte Cassino,where he was captured by the Angevins. According to Ferdinand Gregorovius he spent the next twenty-three years in captivity in Castello di Canosa from 1268 to 1277, and in Castel del Monte from 1277 to 1291. In 1272, his half-sister Eleanor and her husband King Edward I of England came to Sicily on return from the Crusades. Eleanor's attempts to get him released from prison were unsuccessful, but she kept in touch with him until her own death.
Both Eleanor and Charles were dead before Henry was finally released in 1291. He returned to Castile in 1298, where he was appointed Regent for his grandnephew, King Ferdinand IV. He married Juana Núñez de Lara, but had no known legitimate children before his death in 1304. According to tradition (Anales Eclesiásticos y Seculares, page 149) he had a son, out of wedlock, with a lady called Mayor Rodríguez Pecha, daughter of the lord (Alcaide) of the castle of Zamora. This son was called Enrique Enriquez de Sevilla, who became Justicia Mayor or Chief Judge of Castile under King Alfonso XI. Recent literary studies attribute the famous tale of chivalry "Amadis de Gaula" to Henry of Castile. He was a poet, a troubadour and a daring warrior. He could have written "Amadis" while imprisoned in Castel del Monte, Terra di Bari, Italy for many years.