Isabelle van Keulen is a Dutch violinist and violist, performing principally as a chamber musician but also as a concert violist. She founded the Isos Quartet in 1995. For more than 20 years, she collaborated with the pianist Ronald Brautigam and the mezzo-soprano singer Christianne Stotijn. In 2012, she became an educator at the Lucerne School of Music. Since 2017, she has been artistic director at Deutsche Kammerakademie Neuss in Germany.