Willy Zwaenepoel is a world leader in experimental software systems. He is well known for his groundbreaking work on distributed shared memory and has made fundamental contributions to a variety of subjects, including multicast communication, fault tolerance, Internet servers, graph processing, virtualization, and storage systems. The influence of his work is evidenced by its large number of citations and its translation into production systems. He has received numerous awards for his teaching and research and has mentored young researchers who went to renowned institutions, or who started successful companies.