Peter Grassberger (born 17 May 1940) is a retired professor who worked in statistical and particle physics.
While working at CERN, he realized that reggeon field theory can be viewed as a contact process in the same universality class as directed percolation.
His publications span a variety of topics including reaction-diffusion systems, cellular automata, fractals, Ising model, Griffiths phases, self-organized criticality, and percolation.
He held long-term positions at the University of Wuppertal and at the Forschungszentrum Jülich (Germany).
Other positions that lasted between 2 years and 3 months were at CERN, at the Universities of Kabul, Nice, Calgary, Rome and Utrecht, the Weizmann Institute, the Max Planck Institute for the Physics of Complex Systems in Dresden, the Istituto nazionale di ottica [it] in Florence, and at the Institute for Advanced Studies in Basic Sciences in Zanjan, Iran.