Duke

Duke is the title of the male ruler of a duchy or of a male member of the nobility. Traditionally, duke is the highest level of nobility, ranking just below the monarch.

The only current European Duchy is the Grand Duchy of Luxembourg. Its current Grand Duke is Henri.

Non-royal dukes exist some of the present-day European monarchies, including the United Kingdom and Spain. In other European monarchies, including Belgium and Sweden, the title of duke is given to members of the royal family (e.g., the heir to the Belgian throne is titled Duke of Brabant).