Klaas Hoek is a Dutch organist and composer who mainly focuses on music for harmonium and clavichord, with an emphasis on contemporary work. As a music historian, he specializes in harmonium construction. He is also the designer of a wind harmonium, a sound installation situated in Friesland. Hoek often plays together with improvising singer Greetje Bijma. He was an organist at the Grote Kerk in Harlingen and director of the Music School Westerkwartier in Leek.