The monarchic title Grand Duke is or was used in some independent nations or states in Europe, particularly:

• in present-day Luxembourg
• historically for the sovereigns (i.e. monarchic heads of state) of former independent countries like Tuscany (from 1569 to 1860, now part of Italy), Baden, Oldenburg, Saxe-Weimar, Mecklenburg-Schwerin etc. (Grand Duchies from 1815 to 1918 and all now part of Germany)
• formerly also for some nations in eastern and north-eastern Europe, such as Finland and Lithuania.