Grand Duke William IV of Luxembourg, Guillaume Alexandre (April 22, 1852 - February 25, 1912) was the eldest child of Grand Duke Adolf of Luxembourg. He became Grand Duke when his father died on November 17, 1905.
On June 21, 1893, he married Maria Ana of Portugal. The couple had six daughters, the eldest of which, Marie-Adélaïde (1894-1924), was declared Heir Apparent on July 10, 1907, and eventually became the first reigning Grand Duchess of Luxembourg. The second daughter Charlotte (1896-1985), then succeeded her on the throne in 1919.
Their other daughters were:
* Princess Hilda (1897 - 1979), who married HSH Adolf, Fürst zu Schwarzenberg.
* Princess Antoinette (1899 - 1954), who married Crown Prince Rupprecht of Bavaria.
* Princess Elizabeth (1901 - 1950), who married HSH Ludwig Philipp, Prince von Thurn und Taxis.
* Princess Sophia (1902 - 1941), who married HRH Ernst of Saxony, son of Frederick Augustus III of Saxony.