This name, with variant spellings Kelliher, Kalaher Kelleher etc., is an Anglicized form of the Old Gaelic O'Ceileachair. The Gaelic prefix "O" indicates "male descendant of", plus the personal byname Ceileachair meaning "companionable" or "uxorious". The O'Ceileachair clan were of the population group, Dal gCais, otherwise called the Dalcassians, and they belonged to the ancient territory of Tuathmhumhan comprising most of the modern County Clare with adjacent parts of Counties Limerick and Tipperary. The family claim descent from one, Ceileachar, nephew of Brian Boru, High King of Ireland, 1002 - 1014. Maolmuire Mac (son of) Ceileachair compiler of the ancient "Book of the Dun Cow" belonged to the pre surname period. In the 14th Century the clan left their original habitat and settled in Counties Cork and Kerry where the name is most numerous today. In February 1855 Cornelius, son of Andrew Keller and Mary Tuomey, was christened in Ballyvourney Roman Catholic Church, County Cork and on June 28th 1865 Catherine, a daughter was born to Daniel Keller and Catherine Rahilly in Boherbue, County Cork, Ireland. The first recorded spelling of the family name is shown to be that of Donough O' Ceileachair, Bishop of Ossery, which was dated 1048, "Ecclesiastical Records of Ireland", during the reign of High Kings of Ireland, "with Opposition", 1022 - 1166. 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.