Sexton, ó Seasnáin A Gaelic surname, a sept of the Dál gCais in Thomond. The anglicised form appeared early in the city of Limerick. There is also an English surname, being a reference to the officer in a church in charge of the sacred vessels and vestments. In 1890 the surname was principally found in Cork, Clare, Limerick and Cavan, and the estimated number of bearers was 1,930. In the United States Sexton is the 680th most numerous surname with an estimated 46,750 bearers.