Castlebay is the main village and a community council area on the island of Barra in the Outer Hebrides, Scotland. The village is located on the south coast of the island, and overlooks a bay in the Atlantic Ocean dominated by Kisimul Castle, as well as nearby islands such as Vatersay. Castlebay is also within the parish of Barra. The village is located on the A888, which serves as a circular road around Barra. In 1971, it had a population of 307.