Recorded in several forms including Geoghegan, Geoghan, Gegan, Gagan, Gahagan, Geogan, this ancient and distinguished surname is Irish. The modern spellings are developments of the pre 10th century Gaelic surname "MagEochagain", which translates as 'The son of of the horseman'. Traditionally, Irish family names were taken from the original chief of the clan, who in this case was an illustrious warrior. They are or were, usually prefixed by Mac, denoting "son of," and originally written as "Mag" before a vowel, or O', the grandson or male descendant of. The clan were of the southern Ui Neill, an ancient population group which claimed descent from the famous 6th century King Niall of the Nine Hostages. Their territory was located in the barony of Moycashel, County Westmeath, with the chiefs' seat near Kilbeggan. Fifteen chiefs of the name are mentioned in ancient annals of Ireland between 1291 and 1450. Their estates were very extensive, the most important being at Castletown near Mullingar, now called Castletown-Goeghegan. A branch of the family settled at Bunowen, in County Galway, where the name was shortened to Geoghan and Gegan. An example of the surname recording is that on July 7th 1796 of Peter Geoghegan and Margaret Brogan who were married at Mullingar, County Westmeath. The coat of arms has the blazon of a silver shield charged with a red lion rampant between three red dexter hands couped at the wrist. The first recorded spelling of the family name is shown to be that of Teag Mag Eochagain, which was dated 1291, in the "Annals of the Four Masters". Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.