Prince Johan Willem Friso of Orange-Nassau and his wife Maria Louisa of Hesse-Kassel had two children (she was pregnant with their son stadholder William IV) when he drowned. Those two children are the ancestors of all the currently reigning sovereign in Europe if you leave out the Vatican and Andorra.
With queen Sofia marrying into the Spanish house there has come an additional to the Nassau's through her mother who was a princess of Hannover and the granddaughter of Wilhelm II who descended from William the Silent in multiple lines.
Juan Carlos is also a descendant of William IV through Alfonso XIII's mother Maria Christina, her mother archduchess Elisabeth Franciska was the daughter of Maria Dorothea of Wurtemberg. Her mother was Henrietta of Nassau-Weilburg a granddaughter of stadholder William IV through her mother Carolina of Orange-Nassau and her husband Karl-Christian of Nassau-Weilburg.
Henrietta's brother Alexander was the father of Duke Franz von Teck and the grandfather of Queen Mary.
The lines from Johan Willem Friso to the sovereign princes of Liechtenstein and Monaco go through his daughter Amelie who married the hereditary prince of Baden.
Is it true that six of the ten reigning monarchs of Europe today descend from the House of Nassau? The Benelux sovereigns are obvious -- especially Luxembourg and the Netherlands; Belgium would be through Queen Astrid (descended from Princess Sophie of Nassau-Weilburg).
I believe all three Scandinavian sovereigns would likewise be descended from the said house, through the same Sophie (the queen consort of King Oscar II of Sweden and Norway).
But the sovereigns of Spain, Great Britain, and the two principalities do not appear to be descended from the Nassaus. Or do they? Can anybody trace the genealogical connections between these four reigning monarchies and this German house?