Hans Werner Ballmann (known as Werner Ballmann; born 11 April 1951) is a German mathematician. His area of research is differential geometry with focus on geodesic flows, spaces of negative curvature as well as spectral theory of Dirac operators Ballmann earned his doctorate from the University of Bonn in 1979, under the supervision of Wilhelm Klingenberg.He currently is a professor at the University of Bonn, and the managing director of the Max Planck Institute for Mathematics in Bonn, Germany, since 2007. He has advised 16 doctoral students at Bonn, including Christian Bär and Anna Wienhard.