Ernest I, Duke of Saxe-Gotha (d. 1675)
Ernest I, called "Ernest the Pious" (25 December 1601 – 26 March 1675), was a duke of Saxe-Gotha and Saxe-Altenburg. The duchies were later merged into Saxe-Gotha-Altenburg.

He was the ninth but sixth surviving son of Johann II, Duke of Saxe-Weimar, and Dorothea Maria of Anhalt. His mother was a granddaughter of Christoph, Duke of Württemberg, and great-granddaughter of Ulrich, Duke of Württemberg.