Sebastián de la Cuadra, 1st Marquess of Villarías

Sebastián de la Cuadra y Llarena, 1st Marquess of Villarías (19 January 1687 – 23 April 1766) was a Spanish statesman. He served as Chief Minister between 1736 and 1746 during the reign of Philip V of Spain.

He was the third son of Simón de la Quadra y Medrano, Síndico General of the Comarca of Las Encartaciones. In 1700, he moved to Madrid, where he was a protégé of future Secretary of State José de Grimaldo. He became in 1719 Mayor of Muskiz, a Basque town exploiting iron ores and local smelters, having two himself, one working as early as the 15th century. But he remained in Madrid and was represented in Muskiz by his brother Agustin. He became a Knight of the Military Order of Santiago in 1730 (sig. 2239) and Oficial Mayor to the Secretary of State in 1731.

In 1736 he became himself First Secretary of State, when José Patiño died. From 1741 he also controlled the Justice Department. For much of this late period in office, Spain was involved in the War of Jenkins' Ear with Britain and the War of the Austrian Succession in Italy. He was replaced by José de Carvajal y Lancáster in December 1746. For his service he was made Marqués de Villarías by King Philip V of Spain on 22 March 1739, an honour awarded sometimes either to outgoing First Ministers or during their tenure.

He was a co-founder of the Real Academia de Bellas Artes de San Fernando in 1744.