Diego López I de Haro

Diego López I de Haro (died 1124×6) was the third Lord of Biscay, and also the ruler of Álava, Buradón, Grañón, Nájera, Haro, and perhaps Guipúzcoa: the most powerful Castilian magnate in the Basque Country and the Rioja during the first quarter of the twelfth century. He was a loyal supporter of Queen Urraca and he fought the invading armies of her estranged husband Alfonso the Battler on two, or perhaps three, occasions.

Diego succeeded his father, Lope Íñiguez, in Biscay (and perhaps Guipúzcoa) on the latter's death in 1093, but Álava went to his brother-in-law Lope González. On the death of García Ordóñez at the Battle of Uclés (1108), the tenencias of Grañón, Nájera and Haro passed to Diego by an act of Alfonso VI. In June 1110 Diego received a grant of privileges from Queen Urraca, acting without the consent of Alfonso the Battler, whereby she gave all his patrimonial lands (that is, lands he owned, not fiscal lands he governed on behalf of the crown) complete immunity from confiscation. In August Urraca, then advancing with her army on Zaragoza, confirmed some rights and privileges of the monastery of San Millán de la Cogolla, an act confirmed by the three most important magnates of the region: Sancho, Count of Pamplona, Diego, described as senior in Nagera, and Íñigo Jiménez de los Cameros, dominante in Calahorra. At that time Íñigo Jiménez was also ruling Buradón. After Lope González's death in 1110 and before 1113 Diego succeeded to Álava and re-united all his father's tenencias. It was Diego who first began using the toponymic "de Haro", which became the family name.

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