Alfonso XI of Castile (d. 1350)
Alfonso XI (13 August 1311 – 26 March 1350), called the Avenger (el Justiciero), was the king of Castile, León and Galicia. He was the son of Ferdinand IV of Castile and his wife Constance of Portugal. Upon his father's death in 1312, several disputes ensued over who would hold regency, which were resolved in 1313.

Once Alfonso was declared an adult in 1325, he began a reign that would serve to strengthen royal power. His achievements include the victory in the Battle of Río Salado over Granadans and Marinids and the Castilian control over the Strait of Gibraltar.