The Plöckenstein (Czech: Plechý) is a mountain, 1,379 m (AA) high, in the Bohemian Forest on the Austro-Czech border.

Northeast of, and below the summit on Czech soil, is the lake of Plöckensteiner See, the southernmost of eight glacial lakes in the Bohemian Forest; the northern mountainside is the core zone of the Bohemian Forest National Park (Šumava National Park).

About 7 km northeast, in the Czech Republic, is the western end of the Lipno Reservoir.

The Plöckenstein lies about 1.3 km east of the tripoint between Germany, Austria and the Czech Republic.

During the Cold War the border area of the Bohemian Forest was inaccessible to citizens of the Eastern Bloc because the Iron Curtain ran through it.