Walter Fiers (31 January 1931 in Ypres, West Flanders – 28 July 2019 in Destelbergen) was a Belgian molecular biologist. He obtained a degree of Engineer for Chemistry and Agricultural Industries at the University of Ghent in 1954, and started his research career as an enzymologist in the laboratory of in Ghent. In 1956–57, he worked with in Copenhagen (Denmark). In 1960, he obtained a fellowship from the Rockefeller Foundation and joined the group of as a postdoc. At the California Institute of Technology Walter Fiers was exposed to Molecular Biology, which was then just developing, studying viral DNA. He demonstrated the physical, covalently closed circularity of Bacteriophage PhiX-174 DNA. In 1962, Fiers moved to Madison, Wisconsin, to work in the laboratory of future Nobel laureate,