His Royal Highness Jean I Benoit Guillaume Robert Antoine Louis Marie Adolphe Marc d'Aviano. Grand Duke of Luxembourg (born 5 January 1921) ruled Luxembourg from 1964 to 2000. His full title is "by the Grace of God, Grand Duke of Luxembourg, Duke of Nassau, Prince of Bourbon-Parma, Count Palatine of the Rhine, Count of Sayn, Königstein, Katzenellenbogen and Diez, Burgrave of Hammerstein, Seigneur of Mahlberg, Wiesbaden, Idstein, Merenberg, Limburg and Eppstein."

He became grand duke when his mother, the Grand Duchess Charlotte, abdicated in 1964. He was married on 9 April 1953 to Her Royal Highness Princess Joséphine-Charlotte of the Belgians, who was born on 11 October 1927, daughter of Leopold III, King of the Belgians.

Grand Duke Jean abdicated on 7 October 2000, and was succeeded by his son Grand Duke Henri of Luxembourg.