Mary Lou Williams (1910-1981) was an American jazz pianist, arranger, and composer. She was a prolific composer, with hundreds of both jazz charts and fully-notated works. ​ She began to play piano at the age of three in her hometown of Pittsburgh, and was performing to support her family by the age of six. She later performed with Duke Ellington's early band 'The Washingtonians," and was soon performing and arranging songs for her future husband John Overton Williams, Earl H