Julianus Marie August de Boeck (Merchtem, Belgium, May 9, 1865 – Merchtem, October 9, 1937) was a Flemish composer, organist and music pedagogue. He was the son of organist and director Florentinus (Flor) De Boeck (1826-1892) From 1880 he studied organ at the Royal Conservatory of Brussels under Alphonse Mailly, whose assistant he became until 1902.In 1889 he met the young Paul Gilson who became a close friend and, despite being the same age, his teacher for orchestration. Gilson encouraged de Boeck's composition work.