Ernest I
Ernest I or Ernst I can refer to:
- Ernest I, Duke of Swabia
- Ernest I, Prince of Anhalt-Dessau
- Ernest I, Duke of Brunswick-Lüneburg, Ernest the Confessor
- Ernst I, Duke of Saxe-Coburg-Altenburg, Ernest the Pious
- Ernst I, Duke of Saxe-Coburg and Gotha, father of Prince Albert, the consort of Queen Victoria
- Ernst I, Prince of Hohenlohe-Langenburg
- Ernest Augustus I, Duke of Saxe-Weimar-Eisenach
- Ernest Frederick I, Duke of Saxe-Hildburghausen
- Ernest Günther I, Duke of Schleswig-Holstein-Sonderburg-Augustenburg
- Ernst Ludwig I, Duke of Saxe-Meiningen