Roma) jazz guitarist Jean Baptiste "Django" Reinhardt was the first significant jazz musician who was not American. He is one of, if not the best, guitar player I ever heard. But don't take my word for it, check out the Influence on and admiration by other musicians section of Wikipedia's essay. With little doubt, Django influenced elements of the popular music of every generation that followed his death in 1953.
Djangomania! covers not only the story of Django's life and work, but also tracks his influence today. Hats off, again, to the Sundance Channel for dedication to airing groundbreaking music documentaries.
Here's a little taste of Django and The Quintet of the Hot Club of France performing Minor Swing: