Jacobus Vaet (born probably in 1529 in Kortrijk or Harelbeke; died January 8, 1567, in Vienna) was a Franco-Flemish composer, singer, and conductor of the late Renaissance. The composer Nicolas Gombert had a major influence on him during this period. After serving as a choirboy at the Church of Our Lady in Kortrijk in 1543, he studied at the University of Leuven. In 1549, he became a member of Emperor Charles V’s court choir; the following year, he was listed there as a married tenor singer. In late 1551 or early 1552, Jacobus Vaet left the emperor’s service and joined the court orchestra of Archduke Maximilian in Vienna, where he remained until his death. In 1554, he was appointed Kapellmeister there.

Jacobus Vaet belongs to the generation of Giovanni Pierluigi da Palestrina and Orlando di Lasso; his compositional style occupies an intermediate position between theirs and that of the preceding generation of Nicolas Gombert and Jacobus Clemens non Papa. The bulk of his output consisted of motets. All of Vaet’s masses are parody masses based on his own or others’ compositions. Harmonically, Vaet frequently employs bold dissonances arising from the use of augmented sixths and octaves.