Theodor Wolfgang Hänsch (born 30 October 1941) is a German physicist. He received one fourth of the 2005 Nobel Prize in Physics for "contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique", sharing the prize with John L. Hall and Roy J. Glauber. Hänsch is Director of the Max-Planck-Institut für Quantenoptik (quantum optics) and Professor of experimental physics and laser spectroscopy at the Ludwig-Maximilians University in Munich, Bavaria, Germany.