Ernest Augustus I, Duke of Saxe-Weimar (German: Ernst August I; 19 April 1688 – 19 January 1748) was a duke of Saxe-Weimar. In 1741, he became the duke of Saxe-Weimar-Eisenach.
| Ernest Augustus I | |
|---|---|
 | |
| Duke of Saxe-Weimar | |
| 1707–1748 | |
| Predecessor | Wilhelm Ernst with John Ernst III |
| Successor | Ernest Augustus II |
| Co-ruler | Wilhelm Ernst |
| Duke of Saxe-Eisenach | |
| 1741–1748 | |
| Predecessor | Wilhelm Heinrich |
| Successor | Ernest Augustus II |
| Born | (1688-04-19)19 April 1688 Weimar |
| Died | 19 January 1748(1748-01-19) (aged 59) Eisenach |
| Spouse | Eleonore Wilhelmine of Anhalt-Köthen Sophie Charlotte of Brandenburg-Bayreuth |
| Issue | Wilhelm Ernst, Hereditary Prince of Saxe-Weimar Princess Wilhelmine Auguste Johann Wilhelm, Hereditary Prince of Saxe-Weimar Princess Charlotte Agnes Leopoldina Princess Johanna Eleonore Henriette Ernestine Albertine, Countess of Lippe-Alverdissen Bernhardina, Princess of Schwarzburg-Rudolstadt Prince Emmanuel Frederick Karl August Eugen, Hereditary Prince of Saxe-Weimar Ernest Augustus II, Duke of Saxe-Weimar-Eisenach Princess Eleonore Christiane Princess Johanna Auguste Ernestine, Duchess of Saxe-Hildburghausen Prince Ernst Adolf |
| House | House of Saxe-Weimar-Eisenach |
| Father | Johann Ernst III, Duke of Saxe-Weimar |
| Mother | Sophie Auguste of Anhalt-Zerbst |
| Religion | Lutheranism |