Michael Joseph "Joe" 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 a club 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. Sullivan's recording career began late in 1927 when he joined McKenzie and Condon's Chicagoans. Other musicians included Jimmy McPartland, Frank Teschemacher, Bud Freeman, Jim Lanigan and Gene Krupa.