The Symphony No. 8 in E-flat major by Gustav Mahler is one of the largest-scale choral works in the classical concert repertoire. As it requires huge instrumental and vocal forces it is frequently called the "Symphony of a Thousand", although the work is normally presented with far fewer than a thousand performers and the composer disapproved of it. The work was composed in a single inspired burst at his Maiernigg villa in southern Austria in the summer of 1906. The last of Mahler's works that was premiered in his lifetime, the symphony was a critical and popular success when he conducted the Munich Philharmonic in its first performance, in Munich, on 12 September 1910.

Gustav Mahler was an Austro-Bohemian Romantic composer, and one of the leading conductors of his generation. As a composer he acted as a bridge between the 19th-century Austro-German tradition and the modernism of the early 20th century. While in his lifetime his status as a conductor was established beyond question, his own music gained wide popularity only after periods of relative neglect, which included a ban on its performance in much of Europe during the Nazi era. After 1945 his compositions were rediscovered by a new generation of listeners; Mahler then became one of the most frequently performed and recorded of all composers, a position he has sustained into the 21st century.