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. The organist Johann Ulich was his assistant.
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.