Costelloe (Irish: Casla) is a Gaeltacht village between Inverin (Indreabhán) and Carraroe (An Cheathrú Rua) in western County Galway, Ireland. It lies on the R336 road beside Clynagh Bay. Casla is the headquarters of RTÉ Raidió na Gaeltachta. Casla means "(twisting) creek" or "inlet from the sea" in Irish.