This is an Anglo Norman French patronymic i.e., 'the son of Gerald'. The Anglo\Norman\French prefix 'fi(t)z' indicates 'son of', plus the personal name Gerald, a compound of the elements 'geri' a spear and 'wald', rule. There are over thirteen thousand namebearers in Ireland, the name having been introduced at the time of the Anglo-Norman Invasion i.e., 1170. The Fitzgeralds of Ireland are all said to be descended from Maurice, son of Gerald (husband of Nesta, Princess of Wales) who accompanied Strongbow. Between the years 1329 and 1601, sixteen Fitzgeralds held the title 'Earl of Desmond'. There were twenty Earls of Kildare from 1316-1766 when they became Dukes of Leinster. One of the most illustrious being Garret Mor Fitzgerald, eighth Earl of Kildare (deceased 1513) of whom Henry V11 is reputed to have said 'let this man govern all Ireland'. The first recorded spelling of the family name is shown to be that of Fitzgerald (Gaelic form Mac (son) Gerailt (Gerald), which was dated circa 1400, The Annals of Ireland, during the reign of King Henry 1V, 'Henry of Bolingbroke', 1399-1413. 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.