Johann Ernst of Saxe-Weimar
Johann Ernst von Sachsen-Weimar is the name of the following people:
- Johann Ernst I (Saxe-Weimar) ( the younger ; 1594–1626), Duke of Saxe-Weimar
- Johann Ernst II (Saxe-Weimar) (1627–1683), Duke of Saxe-Weimar
- Johann Ernst III. (Saxe-Weimar) (1664–1707), Duke of Saxe-Weimar
- Johann Ernst IV (Saxe-Weimar) (1696–1715), Duke of Saxe-Weimar and composer
