The Manfred Symphony in B minor, Op. 58, is a programmatic symphony composed by Pyotr Ilyich Tchaikovsky between May and September 1885. It is based on the poem Manfred written by Lord Byron in 1817. It is the only one of Tchaikovsky's symphonies he completed that is not numbered (the Symphony in E flat is a conjectural work left unfinished by the composer); it was written between the Fourth and Fifth Symphonies.