Sancho III of Castile

Sancho III (1134 – 31 August 1158), called the Desired (el Deseado), was King of Castile and Toledo for one year, from 1157 to 1158. He was the son of Alfonso VII of León and Castile and his wife Berenguela of Barcelona, and was succeeded by his son Alfonso VIII. During the Reconquista, in which he took an active part, he founded the Order of Calatrava. His nickname due to his position as the first child of his parents, born after eight years of childless marriage.

He was the eldest son of King Alfonso VII of León and Castile and Berengaria of Barcelona. During his father's reign, he appears as "king of Nájera" as early as 1149. His father's will partitioned the kingdom between his two sons: Sancho inherited the kingdoms of Castile and Toledo, and Ferdinand inherited León. The two brothers had just signed a treaty when Sancho suddenly died in the summer of 1158, being buried at Toledo.

He had married, in 1151, Blanche of Navarre, daughter of García Ramírez of Navarre, and had two sons:

• Alfonso VIII of Castile, his successor
• infante García, who died at birth in 1156, apparently also resulting in the death of Queen Blanche.

There may also have been an older son who died in infancy.