Links For even more historic and general information on our Brennan Clan, check out these links: Brennan Clan History and Links Walter Brennan (Most successful character actor in America) The Brennans of Connacht by Pat Brennan The National Archive Census of Ireland 1901 to 1911 General Register Office for the Republic of Ireland Public Record Office of Northern Ireland General Register Office for Northern Ireland Church of Ireland Geneology Information Presbyterian Historic Society of Ireland National Library of Ireland Discover Ireland Irish Military Archive