Mary Elizabeth Hallock-Greenewalt (Sept. 8, 1871 – Nov. 27, 1950) was an inventor and pianist who performed with the Philadelphia and Pittsburgh symphonies as a soloist. She is best known for her invention of a type of visual music she called Nourathar. Thomas Eakins painted her portrait in 1903, currently in the Roland P. Murdock Collection of the Wichita Museum of Art.