This interesting surname is of early medieval Irish origin, and is an Anglicized form of the Gaelic "O hAilleachain", descendant of Ailleachan. "Ailleachan" is a personal name from a diminutive of "aille", beauty. Traditionally, Irish family names are taken from the heads of tribes, or from some illustrious warrior, and are usually prefixed by "O", grandson, male descendant of, or "M(a)c", denoting "son of". The surname is more usually spelt Hallahan or Hallihane, and is the name of an old but not very numerous Munster family belonging primarily to Co. Cork, but well established as O'Hallaghan, also in Co. Waterford, in the 16th Century, as evidenced by the Tudor Fiants and Chancery Rolls. The first recorded namebearer (see below), was among a number of leading gentlemen of Co. Kildare who received "pardons". Professor John Halahan (1753 - 1813), an original member of the Dublin College of Surgeons, was of a Co. Cork family. Recordings of the surname from Irish Church Registers include; the christening of Ellen, daughter of Cornelius and Narry Hallihan, on November 24th 1817, at Inchigeela, Co. Cork, and the christening of John, son of John and Ellen Hallihan, on January 5th 1827, at Castleventry, Co. Cork. The first recorded spelling of the family name is shown to be that of William O'Halegan, which was dated 1597, in the "Records of Co. Kildare", during the reign of Queen Elizabeth 1, known as "Good Queen Bess", 1558 - 1603. 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.