Plechý / Plöckenstein, Border mountain summit between Mühlviertel and South Bohemia, Austria and Czech Republic.

Plöckenstein (Czech: Plechý) is a 1379 m granite mountain on the Austro-Czech border, the highest summit of the Bohemian Forest in both countries and of the Mühlviertel and South Bohemia. Its rounded summit sits on a ridge of two-mica granite; the northeast face drops 211 m into the glacial cirque holding Plöckensteiner See. The Adalbert Stifter obelisk stands not on the summit but on a rock ledge above the lake.

The mountain was closed to visitors during the Cold War because of fortifications built along the Iron Curtain. After 1989, these barriers were removed and the border region became accessible again.

The Adalbert Stifter monument is a 14.5 m obelisk built in 1876–1877 on a rock ledge above the Plöckensteinsee, not on the summit. It honours the "poet of the Bohemian Forest", whose story Der Hochwald made the mountain known. The lake below is the southernmost of the eight glacial lakes of the Bohemian Forest.

The summit is reached by the red ridge trail no. 0148, the Šumava long-distance footpath, which links it westward with Trojmezná and Třístoličník and eastward with Smrčina. The Austrian Nordwaldkammweg also crosses the mountain. The tripoint of Germany, Austria and the Czech Republic lies about 1.3 km west of the summit.

Below the summit lies Plöckensteiner Lake, a glacial lake located within the protected core zone of Bohemian Forest National Park. This small lake surrounded by rocks and mountain forest reveals the ice age past of the region.