Eleanor of Toledo, born Doña Leonor Álvarez de Toledo y Osorio, was a Spanish noblewoman and Duchess of Florence as the first wife of Cosimo I de' Medici. A keen businesswoman, she financed many of her husband's political campaigns and important buildings like the Pitti Palace. She ruled as regent of Florence during his frequent absences: Eleanor ruled during Cosimo's military campaigns in Genoa in 1541 and 1543, his illness from 1544 to 1545, and again at times when the war for the conquest of Siena. She founded many Jesuit churches. She is credited with being the first modern first lady or consort.