Diego Guzmán de Haros (1566 – 21 January, 1631) was a cardinal of the Roman Catholic Church from 1629 to 1631.
Diego Guzmán de Haros was born in Ocaña in 1566. He was educated at the University of Salamanca, completing doctorates in theology and law.
After he was ordained as a priest, he became chaplain of the Discalced Franciscans in Madrid. In 1608, he became a royal chaplain in the household of Philip III of Spain. He became a member of the Supreme Council of the Spanish Inquisition in August 1613. He also became a canon in the cathedral chapter of Cathedral of Toledo. The king also named him preceptor for his daughters the infantas Maria Anna of Spain.
He was named Patriarch of the West Indies on March 14, 1616 and Titular Archbishop of Tyre on April 18, 1616. He was subsequently consecrated as a bishop. On June 30, 1620, Pope Paul V named him Commissary Apostolic of the Bull of the Crusade he issued that year. He was appointed Archbishop of Seville on September 15, 1625.