Charles Frederick (German: Karl Friedrich; 2 February 1783 – 8 July 1853) was the reigning Grand Duke of Saxe-Weimar-Eisenach.

Born in Weimar, he was the eldest son of Charles Augustus, Grand Duke of Saxe-Weimar-Eisenach and Luise Auguste of Hesse-Darmstadt.

His capital, Weimar, continued to be a cultural center of Central Europe, even after the death of Goethe in 1832.

Due to the intervention of Liszt, the composer Richard Wagner found refuge in Weimar after he was forced to flee Saxony for his role in the revolutionary disturbances there in 1848-49.

In St. Petersburg on 3 August 1804, Charles Frederick married the Grand Duchess Maria Pavlovna of Russia, daughter of Emperor Paul I.