Stephanie Alfonso of Castile

Stephanie's date of birth must have occurred between 1139, when the relationship between Alfonso and her mother began,[1] and 1148, the year in which Alfonso confers privileges in favor of Urraca and his daughter.[1][2]

In 1157, Stephanie's father died while returning from an expedition and his kingdoms were partitioned between her legitimate half-brothers, Sancho III of Castile and Fernando II of León. Stephanie would marry Fernando Rodríguez de Castro, head of the House of Castro. Nicknamed "the Lion" in his native Castile, he was exiled as a consequence of his family's struggles with the Lara family and joined the service of Ferdinand II in León, where he was dubbed "the Castilian". Ferdinand would name him governor, at different times, of Cuéllar, Dueñas, Valladolid, Toro and Asturias, and he eventually became Ferdidand's mayordomo mayor. He had divorced his first wife, Constanza Osorio, daughter of Count Osorio Martinez, who was killed fighting Castro at the Battle of Lobregal in 1160. For his services, King Ferdinand rewarded him with Stephanie's hand, also granting them the infantazgo of León. She bore her husband a son, Pedro Fernández de Castro.

On 1 July 1180, Stephanie was murdered by her husband, Fernando, who according to some sources listed, while others have left no record of the event, it is assumed that his wife had been unfaithful and murdered. When Fernando first heard about his wife's affair with an unknown man, he watched the lovers. He then later stabbed the man to death. Later, he entered the chambers of his wife and stabbed her to death. When Fernando realized what the situation had turned to, he begged for forgiveness from his brother-in-law the King. The King did not punish his brother-in-law for the murder.

Stephanie was buried in the basilica of San Isidoro de León. She left two young children.