Castalia is a village in Erie County, Ohio, United States. The population was 935 at the 2000 census. It is part of the Sandusky, Ohio Metropolitan Statistical Area.
Castalia is located at 41°23′59″N 82°48′26″W / 41.39972°N 82.80722°W / 41.39972; -82.80722 (41.399805, -82.807176).
According to the United States Census Bureau, the village has a total area of 1.0 square miles (2.7 km²), of which, 1.0 square miles (2.7 km²) of it is land and 0.95% is water.