Despite being two years younger than the other Sonny Boy Williamson (II), this one (born John Lee Curtis Williamson in Tennessee) was on the scene in the '30s and '40s before his murder in a robbery after a gig. He was only 34.
His early travels came alongside Sleepy John Estes and Yank Rachell. Settling in Chicago around '34, his first record was "Good Morning, School Girl" (1937), which became a blues standard for ever after. He cut a bunch of sides for the Bluebird label as a leader and also appeared as a sideman on hundreds of recordings. His bands in the '40s included a young Muddy Waters, as well as Tampa Red.
He popularized the blues harmonica as a band-leading instrument and inspired many who came after him, including Junior Wells, Little Walter, Billy Boy Arnold and of course the guy who profited from stealing his name, the other Sonny Boy Williamson. His call-and-response vocal with his harmonica set the tend. So here's a shout out to the ORIGINAL Mr Sonny Boy Williamson.