Johann Friedrich Fasch (15 April 1688 – 5 December 1758) was a German violinist and composer.
Fasch was born in the town of Buttelstedt, 11 km north of Weimar, the eldest child of schoolmaster Friedrich Georg Fasch and his wife Sophie Wegerig, from Leißling near Weißenfels. After his father's death in 1700, Fasch lived with his mother's brother, the clergyman Gottfried Wegerig in Göthewitz, and it was presumably in this way that he made the acquaintance of the Opera composer Reinhard Keiser.
Fasch was a choirboy in Weissenfels and studied under Johann Kuhnau at the St. Thomas School in Leipzig. It was in Leipzig in 1708 that he founded a Collegium Musicum. in 1711 he wrote an opera to be performed at the Peter-Paul Festival in Naumburg, and a second one for the festival in 1712.
In 1714, unable to procure aristocratic patronage for a journey to Italy, Fasch instead travelled to Darmstadt to study composition for three months under his former Leipzig prefect Christoph Graupner and Gottfried Grünewald. He then traveled extensively in Germany, becoming a violinist in the orchestra in Bayreuth in 1714, was an amanuensis in Gera till 1719 and from 1719 until 1721 held a court post as organist in Greiz.
His next major post was Prague, where he served for two years as Kapellmeister and court composer to Count Morzin,. In 1722, he "reluctantly accepted the position" of court Kapellmeister at Zerbst, a post he held until his death. (The organist Johann Ulich was his assistant.) Also in 1722, he was invited to apply for the position of Thomaskantor in Leipzig at his alma mater, the St. Thomas School, but he chose to withdraw his name from the competition. The Leipzig opening was eventually filled by Johann Sebastian Bach, who had considerable esteem for Fasch.