Aristide Cavaillé-Coll (born Montpellier, 4 February 1811; died Paris, 13 October 1899) was a French organ-builder. Most organists think of him as the greatest organ-builder of the 19th century, and one of the greatest who ever lived. He invented many new mechanical devices and his organs changed the way that composers could write for the instrument. César Franck, Alexandre Guilmant, and Charles-Marie Widor, in particular, were strongly influenced by the new type of organ that he was building.