This notable Irish surname is an Anglicized form of the Old Gaelic "O'hAileachain", descendant of Aileachan, a male given name derived from "aille", beauty, comeliness. Traditionally, Irish family names are taken from the heads of tribes, revered elders, or some illustrious warrior, and are usually prefixed by "O", grandson, male descendant of, or "Mac" denoting "son of". The great O'hAileachain sept belonged primarily to the Munster county of Cork, and in the process of Anglicization the name has acquired many variant spellings including: Hallihane, (O)'Halleghane, (O)'Hallihane and Halligan. As O'Hallaghan, the name was well established in Co. Waterford in the 16th Century, as evidenced by the Tudor Fiants and Chancery Rolls of that county, and in the Tipperary Hearth Money Rolls the spelling Halligan is used. William O'Halegan was a leading gentleman of Co. Kildare in 1597, and Professor John Halahan (1753 - 1813), an original member of the Dublin College of Surgeons, was of a Co. Cork family. On March 14th 1766 Richard Hallahan, an infant, was christened in Ballyhay, Co. Cork. The first recorded spelling of the family name is shown to be that of O'hAileagain, lector of Armagh, which was dated 1042, in the "Annals of Ulster", 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.