Louis Spohr (5 April 1784 – 22 October 1859) was a German composer, violinist and conductor. Born Ludwig Spohr, he is usually known by the French form of his name outside Germany. Sometimes described as "The Forgotten Master", Spohr was once as famous as Beethoven. As a violinist, his virtuoso playing was admired by Queen Victoria. As a composer he ranks as an historic figure in the development of German music drama and whose greatest triumph was in the oratorio. His orchestral writings and chamber works were once considered on a par with Mozart’s.

A prolific composer, Spohr produced more than 150 works with opus numbers, in addition to a number of works without such numbers. He wrote music in all genres. His nine symphonies (a tenth was left unfinished, but was brought to completion by Eugene Minor and premiered by the Bergen Youth Orchestra) show a progress from the classical style of his predecessors to the programme music of the ninth symphony, Die Jahreszeiten (The Seasons). Between 1803 and 1844 Spohr wrote more violin concertos than any other composer of the time, fifteen in all. Some of them are formally unconventional, such as the one-movement Concerto No. 8, which is in the style of an operatic aria, and which is still periodically revived (Jascha Heifetz championed it), most recently in a 2006 recording by Hilary Hahn. There are two double-violin concertos as well. Better known today, however, are the four clarinet concertos, all written for the virtuoso Johann Simon Hermstedt, which have established a secure place in clarinettists' repertoire.

Among Spohr's chamber music is a series of no fewer than 36 string quartets, as well as four interesting double quartets for two string quartets. He also wrote an assortment of other quartets, duos, trios, quintets and sextets, an octet and a nonet, works for solo violin and for solo harp, and works for violin and harp to be played by him and his wife together.