Which composer is often called 'The Father of the String Quartet'?

Franz Joseph Haydn (March 31, 1732 – May 31, 1809) was an Austrian composer. He was one of the most important, prolific and prominent composers of the classical period. He is often called the “Father of the Symphony” and “Father of the String Quartet” because of his important contributions to these genres. He was also instrumental in the development of the piano trio and in the evolution of sonata form.

The Classical string quartet form was created by Joseph Haydn in the late 1750s. He is described as the "father" of the string quartet because in his total of sixty-eight quartets he developed this genre into its first maturity. The string quartet features four parts for two violins, viola and cello.