This interesting surname is of Irish origin, and is an Anglicized form of the Old Gaelic "MacAodhagain". The Gaelic prefix "mac" denotes "son of", and the personal name "Aodhagain" is a diminutive of "Aodh", "fire", originally the name of a pagan god. The great MacAodhagain sept originated in the ancient territory of Ui Maine (comprising mid-Galway and south Roscommon), where they held the hereditary office of "ollav" or lawyer to the ruling families. A branch of this important Brehon (law-giving) family settled in the Leinster counties of Wicklow and Dublin, where the name was Anglicized Keegan, the original Anglicized form being Egan. Following the destruction of the Old Gaelic order, this sept held high office in the Church, and several of its members distinguished themselves in battle. On November 22nd 1792, Betty, daughter of William Keegan, was christened in Athy, Co. Kildare. Between January 1846 and June 1847 thirty-two Keegans are known to have arrived in New York as famine immigrants. The family Coat of Arms is a shield divided quarterly red and gold, with a silver tower supported on either side by a man in complete armour holding in the interior hand a battle-axe all proper, in the first and fourth quarters, and a green bend changed with three silver plates in the second and third. The first recorded spelling of the family name is shown to be that of Sarah Egan, which was dated 1226, marriage to Thomas L'Estrange, at Killaloe, Co. Clare, during the reign of King Henry 111 of England, known as "The Frenchman", 1216 - 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.1272.