The Grossglockner (Großglockner ˈɡʁoːsˌɡlɔknɐ), or just Glockner, is, at 3,798 metres above the Adriatic (12,461 ft), the highest mountain in Austria and the highest mountain in the Alps east of the Brenner Pass. It is part of the larger Glockner Group of the Hohe Tauern range, situated along the main ridge of the Central Eastern Alps and the Alpine divide. The Pasterze, Austria's most extended glacier, lies on the Grossglockner's eastern slope.
The characteristic pyramid-shaped peak actually consists of two pinnacles, the Grossglockner and the Kleinglockner (, from German: groß, "big", klein, "small"), separated by the Glocknerscharte col.
The name Glocknerer is first documented in a 1561 map designed by the Viennese cartographer Wolfgang Lazius. The denotation Glogger is mentioned a 1583 description of the Tyrolean Kals legal district, then referring to the whole ridge south of the Alpine main chain. In the 1760s, the Atlas Tyrolensis listed a Glockner Berg, the prefix Gross- ("great") is not mentioned before the first expedition in 1799.
According to the scholar Belsazar Hacquet (1735–1815), Glockner is possibly derived from German: Glocke ("bell"), referring to the mountain's characteristic shape. It may also be a Germanised version of the Alpine Slavic word Klek ("mountain"), as maintained in the Slovene name Veliki Klek.
The Grossglockner lies on the border between the Austrian states of Carinthia and Tyrol (East Tyrol). The peak is part of the Glocknerkamm ridge in the Glockner Group that branches off the main chain of the Alps at Eiskögele, heading in a southeasterly direction and forming the boundary between the East Tyrolean municipality of Kals am Großglockner, about in the southwest at , and Carinthian Heiligenblut, about in the northeast at . This boundary is also the watershed between the Kals Valley and its Teischnitz and Ködnitz side valleys on the Tyrolean side and the Möll Valley with the Pasterze glacier on the Carinthian side.