Jef "Joseph" Maes (5 April 1905 in Antwerp – 30 June 1996 in Antwerp) was a Belgian composer and violist.
Encouraged by his friend, André Cluytens, he completed his study at the Flämi conservatory in Antwerp. He studied viola with Napoleon Distelmans; chamber music with Albert van de Vijver; and counterpoint and fuge with Karel Candael.
When he was 23 years old, he composed his first work, which was a romantic Meditation for violin and piano.
After his studies, he was employed for two years as a violist in the opera orchestra in Antwerp; in 1926 he participated in an orchestra under the conductorship of Lodewijk de Vocht, Nieuwe Concerten. In 1930 he was a soloist with the well-known Dierentuin concerts in Antwerp, directed by Flor Alpaerts. Afterwards he was a violist for about 10 years with the Casino Orchestra at Knokke Casino. In 1933 he lectured at the music academy in Boom, Antwerp; ten years later he was appointed director of the academy. From 1942 to 1955 he lectured in harmony teachings at the Royal Flämi Conservatory in Antwerp. He also lectured in chamber music from 1955 to 1970.
Along with Gaston Ariën, J.A. Zwijsen and Steven Candael, Maes founded the Antwerpse Philharmonie (Antwerp Philharmonic Orchestra) in 1955, their first concert given on December 10, 1956. The orchestra is now known as the Royal Flemish Philharmonic or DeFilharmonie.
Beginning in 1961 he led the annual International Music Camp, organized through "youth and music" in Belgium during the summer holidays. He was also a musical mentor in Turnhout.