Charles Augustus, Hereditary Grand Duke of Saxe-Weimar-Eisenach

Charles Augustus, Hereditary Grand Duke of Saxe-Weimar-Eisenach may refer to:
 * Charles Augustus, Hereditary Grand Duke of Saxe-Weimar-Eisenach (1844–1894)
 * Charles Augustus, Hereditary Grand Duke of Saxe-Weimar-Eisenach (1912–1988)