Karlstein may refer to places in:
; Germany:
* Karlstein am Main, a municipality in Landkreis Aschaffenburg, Bavaria
* part of Bad Reichenhall, Bavaria
** a rock with a ruin there
* Karlstein bei Hornberg, a rock in Hornberg, Baden-Württemberg
* part of Regenstauf, Landkreis Regensburg, Bavaria
** Schloss Karlstein, the castle there
* Aussichtspunkt Karlstein, a site above Weinstadt, Baden-Württemberg
; Austria:
* Karlstein an der Thaya, a municipality in Lower Austria, Austria
** Schloss Karlstein, the castle there
** Internierungslager Karlstein an der Thaya, a former internment camp there
; Czech Republic:
* Karlštejn Castle, a 14th-century castle in Central Bohemia
** Karlštejn (Beroun District), městys named after the castle
** Karlštejn, nature reserve nearby the castle
* Hunting castle Karlštejn nearby village Svratouch in Pardubice Region (Chrudim District)
** Karlštejn, administrative part of village Svratouch, named after the hunting castle
** Karlštejn, hill in Žďárské vrchy where the hunting castle is situated
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cs:Karlštejn (rozcestník)
