Alternate use: Reuss River

Reuss is the name of several historical states in today's Thuringia, Germany. Its rulers, the Reuss family, named every male born within it "Heinrich" for centuries.

The Elder Line, the Grafen Reuss zu Greiz, Untergreiz, und Obergreiz, were elevated to princely status in 1778. Its members bore the title Prince Reuss, ältere Linie, or Prince Reuss zu Greiz. The members of this line were numbered sequentially, the last series beginning with Heinrich I (born 1693) and ending with Heinrich XXIV (1878-1927). Reuss Elder Line had an area of 317 km² and a population of 71,000 (1905). Its capital was Greiz.

The Younger Line, the Grafen Reuss zu Gera, zu Schleiz, zu Lobenstein, zu Köstriz und zu Ebersdorf, shared a numbering sequence which began and ended roughly as centuries began and ended. A consequence of this naming system is that the male children within a single nuclear family are not numbered sequentially: The sons of Heinrich LXVII Reuss zu Schleiz were, in order, Heinrich V , Heinrich VIII , Heinrich XI , Heinrich XIV , and Heinrich XVI . This line became princes in 1806, and its members bore the title Prince Reuss, jüngere Linie, though they are also referred to by their branch names (e.g. Prince Reuss zu Koestritz). The designation jüngere Linie was dropped in 1930; the ältere Linie had become extinct as its last member Heinrich XXIV renounced his rights in 1918 and died in 1927 unmarried. Reuss Younger Line had an area of 827 km² and a population of 145,000 (1905). Its capital was Gera.

The two principalities of Reuss "Elder Line" and "Younger Line" were members of the German Confederation, of the North German Confederation, and of the German Empire. In 1919, they were unified as the Republic of Reuss, which was incorporated into the new state of Thuringia in 1920.

Fürsten Reuss, Elder Line, 1778-1918

• Heinrich XI 1778-1800
• Heinrich XIII 1800-1817
• Heinrich XIX 1817-1836
• Heinrich XX 1836-1859
• Heinrich XXII 1859-1902
• Heinrich XXIV 1902-1918 (d.1927)

Fürsten Reuss, Younger Line, 1806-1918

• Heinrich XLII 1806-1818
• Heinrich LXII 1818-1854
• Heinrich LXVII 1854-1867
• Heinrich XIV 1867-1913
• Heinrich XXVII 1913-1918 (d.1928)