Alfonso de Cerda was a Spanish nobleman and a prominent figure in the late 14th century. He was born into a noble family and held the title of Duke of Medina Sidonia. His lineage was significant, as he was a descendant of the House of Guzmán, a powerful family in Spain. Cerda is best known for his involvement in the political affairs of his time, particularly during the reign of King Henry III of Castile. He played a crucial role in various military campaigns and was influential in the governance of his territories, contributing to the stability of the region during a tumultuous period.