Johann Karl August Musäus (29 March 1735 – 28 October 1787) was a German author from Jena. He studied theology at the university of Jena, and would have become the pastor of a parish but for the resistance of some peasants, who objected that he had been known to dance.
From 1760–62 Musäus published in three volumes his first work, Grandison der Zweite (Grandison the Second), afterwards (in 1781–82) rewritten and issued with a new title, Der deutsche Grandison (The German Grandison). The object of this book was to satirize Samuel Richardson's hero Sir Charles Grandison, who had many sentimental admirers in the Holy Roman Empire.
In 1763 Musäus was made master of the court pages at Weimar, and in 1769 he became professor at the Weimar Gymnasium. His second book, Physiognomische Reisen, did not appear until 1778-79. It was directed against Lavater, and attracted much favorable attention. In 1782–86 he published his best work, Volksmärchen der Deutschen, a collection of German fairy tales. Even in this series of tales, the substance of which Musäus collected among the people, he could not refrain from satire. The stories, therefore, lack the simplicity of genuine folk-lore. In 1785 was issued Freund Heins Erscheinungen in Holbeins Manier by Johann Rudolph Schellenberg, with explanations in prose and verse by Musäus. A collection of stories entitled Straussfedern, of which a volume appeared in 1787, Musäus was prevented from completing by his death in Weimar.
The Volksmärchen have been frequently reprinted (Düsseldorf, 1903, &c.). They were translated into French in 1844, and three of the stories are included in Thomas Carlyle's German Romance (1827). Musäus's Nachgelassene Schriften were edited by his relative, August von Kotzebue (1791).