Born 1818, died 1906. King of Denmark 1863-1906. Son of Duke Wilhelm of Schleswig-Holstein-Sonderburg-Glücksburg and Princess Louisa of Hesse-Kassel. Father of King Frederik VIII of Denmark, Queen Alexandra of Britain, Empress Maria Fyodorovna of Russia (born Dagmar), and King George of Greece (born Vilhelm). Husband of Queen Louise of Denmark.
As the first Danish king of the Glücksburg dynasty, Christian IX inherited the kingship from the childless King Frederik VII, last king of the Oldenburg dynasty, as a result of the London Protocol of 1852 and a change to the Danish Law of Succession of 1853. Prior to this, Christian had been merely a "poor relation" of the Danish king, serving as commander of the horse guards - although his succession to the throne had always been considered likely.
Christian IX is probably most famous for being the "Father-in-Law of Europe", a cognomen he gained because his children and grandchildren were married into nearly every major royal dynasty in Europe. The royal families of most European monarchies are his descendants - including Denmark, Britain, Norway, and Greece, as well as most of the defunct monarchies (which still exist, but no longer reign).