William IV, Grand Duke of Luxembourg

William IV (William Alexander; "French: Guillaume Alexandre"; 22 April 1852 – 25 February 1912) reigned as the Grand Duke of Luxembourg from 17 November 1905 until his death. He succeeded his father, Adolphe.
Currently, William is the last monarch of Luxembourg to die while still on the throne.
Titles and styles.
Although the duchy of Nassau was annexed by Prussia after the Austro-Prussian war of 1866, the title of Duke of Nassau was retained by William and his heirs. This does not imply any sovereignty over Nassau.