Sancho II (1036/1038 – 7 October 1072), called the Strong (el Fuerte), was King of Castile (1065–72), Galicia (1071–72) and León (1072).

However, two later Norman chroniclers report that it was Alfonso VI's betrothed, and not Sancho's wife Alberta, who was William's daughter.

After Ferdinand the Great defeated and killed his wife's brother in battle, he was crowned King of León and Castile and called himself Imperator totius Hispaniae ("Emperor of all of Spain").

In 1072, with the aid of his alférez El Cid, at the Battle of Golpejera, he defeated Alfonso, who fled into exile in the Taifa of Toledo.

A Zamoran noble, Vellido Adolfo (also known as Bellido Dolfos), entered Sancho's camp pretending to be a deserter and assassinated him.