Osek (German: Ossek) is a municipality and village in Strakonice District in the South Bohemian Region of the Czech Republic.

The village began to grow around the lord's court, on which a fortress was probably built before 1414.

[4] Until World War I, the villages of Osek, Petrovice, Malá Turná and Rohozná were administrative parts of the municipality of Radomyšl, and Jemnice was a sovereign municipality.

Shortly before World War I, the villages separated and created a new municipality.

The fortress from the 15th century was completely rebuilt into the current pseudo-Baroque castle in 1911.