Stefan Walter Hell (born 23 December 1962) is a Romanian-born German physicist and one of the directors of the Max Planck Institute for Biophysical Chemistry in Göttingen, Germany.He received the Kavli Prize in Nanoscience in 2014 “for transformative contributions to the field of nano-optics that have broken long-held beliefs about the limitations of the resolution limits of optical microscopy and imaging”, together with Thomas Ebbesen, and Sir John Pendry and received the Nobel Prize in Chemistry in 2014 "for the development of super-resolved fluorescence microscopy", together with Eric Betzig and William Moerner.