This name with variant spellings O'Kieran, O'Kerin and Kerrane is an Anglicized form of the Gaelic Irish O'Ciarain and O'Ceirin, a personal name, "Ciar" meaning black or dark brown. In early times this sept controlled the greater part of the present barony of Costello, County Mayo. Today, the name is still very popular in this county. The forms there are Kearns and Kerran. In the medieval period, the name spread to the neighbouring counties of Sligo and Donegal. In Donegal, the form of the name is sometimes found as Kerr. In 1420, an influential branch of the sept settled in County Clare, where the Anglicized form of this branch is (O')Kerin. The tomb of Teige O'Kerin (1685) can be seen in Ennis Abbey. An interesting namebearer was Fr. Moses Kearns, who in the 1780's survived being hanged by the revolutionary mob in Paris through the breaking of the rope. He was one of the leaders in the 1798 rebellion in County Wexford. The first recorded spelling of the family name is shown to be that of Owen O'Kerin, which was dated 1420, in the "Records of County Clare", during the reign of King Henry V, known as "The Victor of Agincourt", 1413 - 1422. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.