German geographer who sought to place geography on a firm philosophical and scientific foundation. He strongly influenced the modern development of geography in Germany.

While completing work on his doctorate at the University of Strasbourg (now in France), Hettner became increasingly absorbed in philosophy. His conception of the nature of geography was rooted in the views of the German philosopher Immanuel Kant, but he was also influenced by a number of the great German geographers. In his view, geography was fundamentally chorology, or the study of geographic distributions over the Earth's surface. It was concerned with human interconnection and interaction with the natural environment, but it should also take into account the arrangement, by area, of the Earth's physical phenomena. The study of local differences in phenomena over the Earth's surface was the keynote of this concept.

Following researches on Chile and Patagonia, Hettner went to Colombia (1882–84) and, after returning to Germany, published his findings on the Colombian Andes (1888). He then turned his attention to the geomorphology of the highlands of Saxony, but in 1888 he returned to South America and began more than a year of travels. The hardship and illness endured in the course of this venture resulted in permanent impairment of his ability to walk. Later field researches took him to Russia (1897), North Africa (1911), and Asia (1913–14). While serving as professor at the University of Heidelberg (1899–1928), Hettner became the mentor of a number of students who distinguished themselves as geographers.

For more than 40 years Hettner's principal medium for disseminating his ideas on the scope and methodology of geography was the influential Geographische Zeitung (“Geographical Journal”), first published in 1899. The first volume of his Grundzüge der Länderkunde (1907; “Foundations of Regional Geography”) dealt with Europe, but its companion volume, on other regions, did not appear until 1924. He also wrote Vergleichende Länderkunde, 4 vol. (1933–35; “Comparative Regional Geography”). One of the major works of geographic literature, the 11-volume Handbuch der Geographischen Wissenschaft (“Handbook of Geographical Science”), completed in 1940, was his conception.