The title "Duke of Luxembourg" refers to a noble title historically associated with the Grand Duchy of Luxembourg. The title has its origins in the medieval period and was held by various noble families. Today, the Grand Duchy is a constitutional monarchy, and the current head of state is the Grand Duke Henri, who is a member of the House of Nassau. The title itself is not currently used in an official capacity, as Luxembourg is governed by a Grand Duke rather than a duke. However, the historical significance of the title remains important in understanding the country's noble heritage and its role in European history.