Sancho IV of Pamplona

Sancho IV, called of Peñalén (c. 1039–1076), was proclaimed king of Pamplona in 1054 after his father García III fell at Atapuerca, ruling under his mother Stephanie's regency. Many western lords went over to León at his accession, while his uncle Ramiro I of Aragon supported him.

A treaty with Ferdinand I in 1062 confirmed his rule in the Rioja, Álava and Biscay. In the War of the Three Sanchos (1067–1068) he lost Bureba, Alta Rioja and Álava to Sancho II of Castile.

On 4 June 1076 his siblings Ramón and Ermesinda had him thrown from a cliff at Peñalén. Aragon and León-Castile then divided Pamplona.