The Gunz or Günz glaciation (German: Günz-Kaltzeit, also Günz-Glazial, Günz-Komplex or (obs.) Günz-Eiszeit), also sometimes the Günz, Gunzian glaciation or Günz glacial stage, is a glacial stage of the Pleistocene epoch. It is the oldest glaciation of the Pleistocene in the traditional, quadripartite glacial classification of the Alps, although there are signs of even older glaciations in the Alpine Foreland, so that today it is reckoned that there were at least eight to 15 glacial periods. The name goes back to Albrecht Penck and Eduard Brückner, who named this ice age after the River Günz in their multi-volume work, Die Alpen im Eiszeitalter ("The Alps in the Ice Age Period") which was published between 1901 and 1909. Its type region is the Iller-Lech Plateau. The Günz followed the Danube-Günz interglacial and was ended by the Günz-Haslach interglacial.
The corresponding stage in North Europe was the Elbe glaciation (Elbe-Kaltzeit or, obsolete, Elbe-Eiszeit).
The Günz is thought to have run from 800 000 to 600 000 years ago. Possible geological correlations suggest it may have begun 900 000 years ago.