The Duke of Montferrat was a noble title in the region of Montferrat, located in northern Italy. This title was held by various rulers from the 10th century until the late 17th century. The dukedom played a significant role in the political landscape of northern Italy, often involved in alliances and conflicts with neighboring states. The most notable Duke of Montferrat was Guglielmo IX, who ruled in the late 15th century. Under his leadership, Montferrat became a center of culture and politics. The dukedom eventually passed to the House of Gonzaga and later became part of the Duchy of Mantua.