Which composer is considered the master of the Lied, or German art song, famously setting Goethe's poem "Erlkönig" to music?

Franz Schubert

Schubert wrote over 600 Lieder during his short career, elevating the genre by giving the piano accompaniment equal importance to the vocalist. 'Erlkönig' is noted for its dramatic use of a driving piano rhythm to represent a galloping horse.