Don Diego Sarmiento de Acuña, Count of Gondomar (Spanish: Don Diego Sarmiento de Acuña, conde de Gondomar; Astorga, November 1, 1567 – Casalarreina, La Rioja, October 2, 1626), was a Spanish (Galician) diplomat. He served as the Spanish ambassador to England from 1613 to 1622 and afterwards, as a kind of ambassador emeritus, Spain's leading expert on English affairs until his death.