Recorded as Renehan, Ronaghan, Rannigan and Ranaghan, this is an Irish surname of great antiquity. It is an anglicized form of the Olde Gaelic name O' Reannachain, the modern Rehehan. The prefix O' indicates male descendant of, plus the personal name 'Reannachain', from "reannach", meaning sharp or keen, plus the diminutive suffix "ain", little. The name is first recorded in an earlier anglicized form in the mid 16th Century, (see below). It appears as Ronaghan in the 1659 Petty's "Census" of Ireland and as such is listed among the principal Irish names in the Barony of Tiranny, County Armagh, the prefix O' having been dropped at an earlier stage. The spellings Ranaghan, Rannigan and Renehan or Renahan are chiefly found in counties Cork and Tipperary. Reverend Doctor Lawrence Renehan (1797 - 1857) of Co. Tipperary, was the president of Maynooth College. The first recorded spelling of the family name is shown to be that of Teag Renaghan of Carlingford, County Louth. This was dated 1560 in the fiants or Letters to the Chancery Authority, during the reign of Queen Elizabeth 1st, known as 'Good Queen Bess', 1558 - 1603. Surnames became necessary when governments introduced personal taxation. In England this was sometimes known as the Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.