Mac Cuillinn is a surname of Irish origin, often associated with the Gaelic name meaning "son of Cuillin." It is primarily found in the province of Ulster, particularly in County Antrim. The name is linked to various historical figures and families in Ireland. The Mac Cuillinn family has a rich heritage, with connections to the ancient Gaelic nobility. They were known for their involvement in local governance and land ownership during the medieval period. Today, the name continues to be recognized in genealogical studies and cultural discussions surrounding Irish ancestry.