Juan de Vega y Enríquez, 6th Señor del Grajal, Viceroy of Navarre (1542), Viceroy and Captain General of Sicily (1547–1557), presidente del Consejo de Castilla, was an ambassador of Charles V, Holy Roman Emperor. He first served as ambassador of Charles V at Rome, where he met Ignatius of Loyola. Esteeming him and Ignatius’ religious order, the Jesuits, when Vega was appointed Viceroy of Sicily he brought Jesuits with him. A Jesuit college was opened at Messina; success was marked, and its rules and methods were afterwards copied in other colleges.
After the Order of Saint John refused to take control of Mehdia, Charles V ordered de Vega to destroy the city to prevent Muslim occupation. De Vega burnt Mehdia, but retaliated against the Order for not accepting the city, and prohibited exportation of wheat to the island of Malta, which was ruled by the Order. To prevent the population from starving, mills were built on Malta.
De Vega died on 20 December 1558.
The astronomer Francesco Maurolico tutored two of Vega’s sons, and Vega served as Maurolico’s principal patron.