St. Athanasius of Mouzaki is a Greek Orthodox church located in Kastoria, Greece. It was built in 1383–84 by the brothers Theodore II and Stoya of the house of Muzaka, a noble Albanian family that controlled the city at the time, and dedicated to St. Athanasius It is considered one of the most important monuments of 14th century Kastoria and is the last church built in Kastoria before its annexation by the Ottoman Empire.

Kastoria is a city in northern Greece in the region of Western Macedonia. It is the capital of Kastoria regional unit, in the geographic region of Macedonia. It is situated on a promontory on the western shore of Lake Orestiada, in a valley surrounded by limestone mountains. The town is known for its many Byzantine churches, Byzantine and Ottoman-era domestic architecture, its lake and its fur clothing industry.