Ernst I, Duke of Saxe-Coburg-Saalfeld, later Duke of Saxe-Coburg-Gotha, (January 2, 1784-January 29, 1844) was the son of Duke Francis Frederick of Saxe-Coburg-Saalfield (1750-1806) and Countess Auguste Reuss zu Ebersdorf und Lobenstein (1757-1831).

On 31 Jul 1817 at Gotha he married Luise, Pss of Saxe-Gotha (1800-1831) from whom he was divorced in 1826.

On December 23,1832 at Coburg he married his niece, Marie, Duchess of Württemberg (1799-1860).

He had two children with his first wife:

• Ernst II, Duke of Saxe-Coburg-Gotha (1818-1893)
• Albert, Prince Consort of Great Britain and Ireland (1819-1861)