Clarke, or Ó Cléirigh in Gaelic, is a very popular surname in Ireland. It is found predominantly in the northern province of Ulster. Its meaning originates in the Gaelic word “Cléireach”, which means ‘clergyman’ or ‘clerk’. Up until the beginning of the twentieth century the names Clery and Clarke were considered interchangeable in some parts of the country. Today, Clarke is the 32nd most numerous name in Ireland.