Mary Lou Williams (born Mary Elfrieda Scruggs; May 8, 1910 – May 28, 1981) was an American jazz pianist, composer, and arranger. She wrote hundreds of compositions and arrangements, and recorded more than one hundred records (in 78, 45, and LP versions). Williams wrote and arranged for such bandleaders as Duke Ellington and Benny Goodman, and she was friend, mentor, and teacher to Thelonious Monk, Charlie Parker, Miles Davis, Tadd Dameron, Dizzy Gillespie, and many others.