Carl Maria Friedrich Ernst von Weber (18-19 November 1786 – 4-5 June 1826) was a German composer, conductor, pianist, guitarist and critic, one of the first significant composers of the Romantic school.

Weber's works, especially his operas Der Freischütz, Euryanthe and Oberon greatly influenced the development of the Romantic opera in Germany. He was also an innovative composer of instrumental music. His compositions for the clarinet, which include two concertos, a concertino, a quintet and a duo concertante, are regularly performed, while his piano music—including four sonatas, two concertos and the Konzertstück (Concert Piece) in F minor—influenced composers such as Frédéric Chopin, Franz Liszt and Felix Mendelssohn. The Konzertstück provided a new model for the one-movement concerto in several contrasting sections (such as Liszt's, who often played the work), and was acknowledged by Igor Stravinsky as the model for his Capriccio for piano and orchestra.

Weber's contribution to vocal and choral music is also significant. His body of Catholic religious music was highly popular in 19th century Germany, and he composed one of the earliest song-cycles, Die Temperamente beim Verluste der Geliebten (Four Temperaments on the Loss of a Lover).