Willem Breuker (4 November 1944[1] – 23 July 2010)[2] was a Dutch bandleader, composer, arranger, saxophonist, and clarinetist.

During the mid-1960s, he played with percussionist Han Bennink and pianist Misha Mengelberg,[3] co-founding the Instant Composers Pool (ICP),[4] with which he regularly performed until 1973.

In 1974, he began leading the 10-piece Willem Breuker Kollektief,[1] which performed jazz in a theatrical and often unconventional manner, drawing elements from theater and vaudeville.

[5] With the group, he toured Western Europe, Russia, Australia, India, China, Japan, the United States, and Canada.

In 1999, BV Haast published the book Willem Breuker Kollektief: Celebrating 25 Years on the Road, which includes two albums.