Abel Decaux (11 February 1869 – 19 March 1943) was a French organist and composer. He studied organ with Charles Widor and Alexandre Guilmant and composition with Jules Massenet. For twenty five years from around 1900 he was organist at the Basilique du Sacré-Cœur, in Paris. In 1923 he went to the United States of America, to teach organ at the Eastman School of Music. He returned to France in 1935, to teach organ at the École César Franck and at the Institut Grégorien in Paris.
Decaux's best known composition (and the only one he ever published), Clairs de lune, is a set of four piano pieces written between 1900 and 1907, and published in 1913. It is remarkably modern for its time and anticipated some of the work of Claude Debussy and Arnold Schoenberg.
Clairs de lune was recorded in 1981 by Turkish pianist Meral Güneyman with works of Frank Bridge and Anton Webern, in 1996 by American pianist Frederic Chiu on a Harmonia Mundi disc with Ravel's Miroirs and Schoenberg's Drei Klavierstücke; and in 2006 by Canadian pianist Marc-André Hamelin on a Hyperion disc with Dukas' Piano Sonata.