In the musician category, Strange Things Afoot at the Circle K selects George Gershwin.
Born in Brooklyn to Russian Jewish immigrant parents, Gershwin began writing songs professionally at the age of 15, and by the time he died at age 39, he had contributed more to the American music landscape than any other composer up to that time.
Early on, he wrote music for the broadway scene in tin pan alley, and then moved on to broadway, where his brother, Ira, served as librettist on much of his most famous work. He also spent time in Paris, largely focusing on more classical projects, and finally he worked in Hollywood doing film scores. His music was distinct in the way it merged classical and jazz elements together, and achieved a musical complexity unlike anything else being done on broadway or Hollywood.
Among his songs, the most iconic include the jazz standards "Not for Me," "Embraceable You," "I Got Rhythm," (which contains a chord progression that's still a favorite amongst jazz musicians today), "Summertime," from his opera Porgy & Bess, "A foggy day," "They Can't Take that Away from Me," "Let's Call the Whole Thing Off", and many others.
But his orchestral works are the most historically significant, with Rhapsody in Blue and American in Paris, the former of which has become synonymous with New York, and is perhaps the most recognizable piece of classical music written in the 20th century.
I think the brilliant thing about Gershwin is that he could fuse the various styles he used without seeming patronizing: in growing up in a very ethnically mixed and vibrant Brooklyn, working in vaudeville from an early age, studying in Paris, he came by all of his influences very sincerely, and his music never sounds like a classical musician experimenting with jazz, or a jazz musician experimenting with classical.