Hermann Wagner (23 June 1840 – 18 June 1929) was a German geographer and cartographer who was a native of Erlangen. He was the son of anatomist Rudolf Wagner (1805–1864) and brother to economist Adolph Wagner (1835–1917).
He received his education at the Universities of Göttingen and Erlangen, and from 1864 to 1876, taught classes in mathematics and natural history at the gymnasium in Gotha. In 1868 he began work as an editor of the statistical section of the Gothaer Almanack for the publishing firm Justus Perthes Geographische Anstalt. Beginning in 1872, with Ernst Behm, he was editor of the geographical/statistical review Die Bevolkerung der Erde.
In 1876 he was appointed chair of geography at the University of Königsberg, and in 1880 was named as successor to Johann Eduard Wappäus as professor of geography at the University of Göttingen. From 1879 to 1920, he was editor of the Geographisches Jahrbuch.
In 1883–84 he published a new edition of Hermann Guthe's Lehrbuch der Geographie. He is also associated with the Sydow-Wagner Methodischer Schulatlas, a school atlas that is named in conjunction with cartographer Emil von Sydow.