Ostrožac Castle (Bosnian, Croatian and Serbian: Tvrđava Ostrožac / Тврђава Острожац) is a castle located in Bosnia and Herzegovina in the Una-Sana Canton just outside the town of Cazin, in the village of Ostrožac. The castle dates back to the 13th century when Ostrožac was part of property of the noble house of Babonić family. In 1592 it was captured by the Ottoman Turks and established as an Ottoman province of Bosnia. The castle was built between 1900 and 1906 by Major of Bihać Lothar Von Berks as a birthday present for his wife, member of the Habsburg family.
Ownership of the castle is still disputed, but citizens of Cazin and Ostrožac are permitted to use the castle grounds for local concerts and entertainment. The castle is slowly being repaired.