James "Jimmy" Dorsey (February 29, 1904 – June 12, 1957) was a prominent American jazz clarinetist, saxophonist, trumpeter, composer, and big band leader. He was known as "JD". He composed the standards "I'm Glad There is You (In This World of Ordinary People)" and "It's the Dreamer in Me".
Jimmy Dorsey was born in Shenandoah, Pennsylvania, the son of a music teacher and older brother of Tommy Dorsey who also became a prominent musician. He played trumpet in his youth, appearing on stage in a Vaudeville act as early as 1913. He switched to alto saxophone in 1915, and then learned to double on clarinet. Jimmy Dorsey played on a clarinet outfitted with the Albert system of fingering, as opposed to the more common Boehm system used by most of his contemporaries including Benny Goodman and Artie Shaw.
With his brother Tommy playing trombone, he formed Dorsey’s Novelty Six, one of the first jazz bands to broadcast. In 1924 he joined the California Ramblers (who were based in New York City). He did much free lance radio and recording work throughout the 1920s. The brothers also appeared as session musicians on many jazz recordings. He joined Ted Lewis's band in 1930, with whom he toured Europe.