Winfried Denk (born 12 November 1957 in Munich) is a German physicist, director of the Max Planck Institute of Neurobiology in Martinsried, close to Munich. He is noted for being the first to implement two-photon microscopy while a postdoctoral fellow in Watt W. Webb's lab at Cornell University in 1990. Denk later (1994) recognized that two-photon microscopy has unique properties for imaging live cells deep in highly scattering tissues. His second major invention is a machine that automatically acquires three-dimensional images at a resolution of a few nanometers. This technique, known as Serial Block-Face Scanning Electron Microscopy (SBFSEM or SBEM), has been commercialized by the company Gatan. For his achievements, Winfried Denk was awarded the Gottfried Wilhelm Leibniz Prize in 2003 and the Kavli Prize in 2012. He was appointed as foreign member of the National Academy of Sciences (NAS) in 2013. He is also a member of the Norwegian Academy of Science and Letters.