Michael Joseph O'Sullivan (November 4, 1906 – October 13, 1971) was an American jazz pianist.
Sullivan was the ninth child of Irish immigrant parents. He studied classical piano for 12 years and at age 17, he began to play popular music in silent-movie theaters, on radio stations, and then with the dance orchestras, where he was exposed to jazz. He graduated from the Chicago Conservatory and was an important contributor to the Chicago jazz scene of the 1920s.... meer