Großer Osser, Mountain summit on border between Bavaria and Bohemia.

The Großer Osser is the 1,293 m summit on the German-Czech border, rising directly above the Osserschutzhaus Albert-Willmann-Haus. Its pointed rocky top of quartz-rich, folded mica schist drops steeply, and the last roughly 50 metres to the cross-border peak must be climbed with light scrambling. The Kleiner Osser (1,266 m) stands west of it, entirely in Bavaria.

The name Osser is of Celtic origin according to recent research. In the 12th century the Osserburg was built on the summit; it is now completely destroyed, and no visible remains of the castle survive on the peak.

Czechs call the Osser "the breasts of the Mother of God", while locals around Lam know their local mountain as the "Matterhorn of the Bavarian Forest". The name Osser is, by recent research, of Celtic origin. Legends also tell of the Osser giant and of a vanished third summit.

Hiking paths from Lohberg, Silbersbach, and Lam lead to the summit, but you will need good physical fitness because of the steep rocky sections. Sturdy footwear and careful footing matter on the uneven terrain.

The Großer Osser's rock cliffs were awarded the Bavarian quality seal "Bayerns schönste Geotope" by the Bavarian State Office for the Environment, which also lists them as geotope 372R010. The garnets in the quartz-rich, strongly folded mica schist reach up to 4 mm in diameter.