Charles Augustus, Hereditary Grand Duke of Saxe-Weimar-Eisenach (Carl August Wilhelm Ernst Friedrich Georg Johann Albrecht; 28 July 1912 – 14 October 1988), was a German prince and head of the grand ducal house of Saxe-Weimar-Eisenach.

He was born in Schloss Wilhelmsthal as the eldest son and heir of Wilhelm Ernst, Grand Duke of Saxe-Weimar-Eisenach, and his second wife, Princess Feodora of Saxe-Meiningen.

When his father died on 24 April 1923, Charles Augustus succeeded him as head of the House of Saxe-Weimar-Eisenach.

[citation needed] Charles Augustus died at Schienen and was succeeded as head of the grand ducal house by his son, Michael.

Charles Augustus was married at the Wartburg Castle on 5 October 1944 to Baroness Elisabeth of Wangenheim-Winterstein (Tübingen, 16 January 1912 – Munich, 15 March 2010), daughter of Othmar Baron von Wangenheim-Winterstein and wife, Baroness Maud von Trützschler.