Johann Friedrich Fasch (15 April 1688 – 5 December 1758) was a German violinist and composer.
Fasch was born in Buttelstedt. He was a choirboy in Weissenfels and studied under Johann Kuhnau at the famous St. Thomas School in Leipzig and later founded a Collegium Musicum in that city. He then traveled throughout Germany, becoming a violinist in the orchestra in Bayreuth in 1714 and holding a court post in Greiz. Also in 1714, Fasch studied composition with Christoph Graupner in Darmstadt. In 1722 he was appointed Kapellmeister at Zerbst, a post he held until his death.
His works include cantatas, concertos, symphonies, and chamber music. None of his pieces were printed in his lifetime, and a large number of his vocal works, including four operas, have been lost. However, he was held in high regard by his contemporaries (Johann Sebastian Bach made manuscript copies of a number of his pieces), and he is today considered an important link between the Baroque and Classical periods.