1493-1519 : Maximilian, husband of, also Emperor of the Holy Roman Empire as Maximilian I
1519-1556 : Charles II, grandson, also Emperor of the Holy Roman Empire as Charles V
Charles V proclaimed the Pragmatic Sanction of 1549 eternally uniting Namur with the other lordships of the Low Countries in a personal union. When the Habsburg empire was divided among the heirs of Charles V, the Low Countries, including Namur, went to Philip II of Spain, of the Spanish branch of the House of Habsburg.
1556-1598 : Philip V, also King of Spain as Philip II
1780-1790 : Joseph I, also Emperor of the Holy Roman Empire as Joseph II
The title was factually abolished in the aftermath of the French Revolution and the annexation of Namur by France in 1795. However, the title remained officially claimed by the descendants of Leopold II until the reign of Karl I of Austria.
1790-1792 : Leopold, brother of, also Emperor of the Holy Roman Empire as Leopold II
1792-1835 : Francis II, also Emperor of the Holy Roman Empire as Francis II
1835-1848 : Ferdinand, also Emperor of Austria as Ferdinand I
1848-1916 : Francis III Joseph, grandson of Francis II, also Emperor of Austria as Francis Joseph I