Sancho IV of Navarre

Sancho Garcés IV
Diploma issued by Sancho IV
King of Pamplona
Tenure	1054–1076
Predecessor	García Sánchez III
Successor	Sancho Ramírez
Died	1076
Spouse	Placencia of Normandy
Issue	García Sánchez García Sánchez Raimundo (illegitimate) Urraca (illegitimate)
House	House of Jiménez
Father	García Sánchez III
Mother	Stephanie of Foix
Religion	Catholicism

Sancho Garcés IV (Basque: Antso IV.a Gartzez; c. 1039 – 4 June 1076), nicknamed Sancho of Peñalén (Basque: Antso Peñalengoa, Spanish: Sancho el de Peñalén) was King of Pamplona from 1054 until his murder in 1076. He was the eldest son of García Sánchez III and his queen, Stephanie, and was crowned king of Pamplona after his father was killed during the Battle of Atapuerca.

Sancho was the eldest son and heir of García Sánchez III and his wife Stephanie. García was killed at the Battle of Atapuerca on 1 September 1054 during a war with the Kingdom of León. Sancho, who was then fourteen years of age, was proclaimed king by the army in the camp by the field of battle with the consent of the king of León, Ferdinand I, also his uncle. Sancho's mother served as his regent until her death on 25 May 1058. Remaining faithful to her husband's policies, she continued to support the monastery of Santa María la Real of Nájera.

Soon after Sancho's accession, many lords in the west of the kingdom went over to the Leonese. Only Íñigo López, lord of Biscay, and Sancho Fortúnez, lord of Pancorbo, remained loyal. On 29 December 1062, Sancho and Ferdinand signed a treaty defining their shared border. Ferdinand was recognised as king of all Castile and Sancho's authority was recognised in the Rioja, Álava, Biscay, and implicitly Guipúzcoa.