Edward Swan Hennessy (24 November 1866 – 26 October 1929) was an Irish-American composer and pianist who lived much of his life in Paris. In his pre-War piano music, he excelled as a miniaturist in descriptive, programmatic music. After joining a group of Breton composers, he developed a reputation as a "Celtic" composer, drawing on his Irish heritage, writing in a style that was unique in a French as well as an Irish context. Even though he has been almost forgotten after 1950, his music was applauded by contemporary French music critics including Henri Collet, Louis Vuillemin, Émile Vuillermoz and Lucien Chevaillier. In some works, he used jazz elements and took inspiration from funfairs and industrial noise, anticipating trends associated with the group of "Les Six".