This unusual and interesting surname has three distinct possible origins, each with its own history and derivation. Firstly, Gagen may be a later form of the Co. Cork surname Goggin or Gaggen, itself a dialectal variant of Cogan, a Welsh locational name from Cogan in the Penarth urban district of Wales, believed to be so called from a Welsh word meaning "bowl", depression". This surname was introduced into Ireland on a large scale after the Norman invasion of 1170, led by Richard de Clare, nicknamed "Strongbow", a Norman living in South Wales. The marriage of Richard de Cogan to Basilie de Riddlesford was recorded in Bray, Co. Wicklow, in 1160. Gagen may also be an Anglicized form of the Old Gaelic "Mag Eochagain", son of Eochaidh, a personal byname meaning "horseman" from "each", horse. This sept, called "(Mac)Geoghegan", in modern Irish, was of the same stock as the famous 6th Century King Niall of the Nine Hostages, and was located in Co. Westmeath, where they held extensive estates, with the chiefs' seat near Kilbeggan. A branch of the family settled in Bunowen, Co. Galway, where the name was shortened to Geoghan and Gegan. Finally, the surname may derive from Gogin, an Old French diminutive nickname for Margaret. On March 20th 1783 Eliza Gaggen and Thomas Mitchell were married in Carrigtohill, Co. Cork, and on December 11th 1872 Anne Gagen married a James Fenn at St. Paul's, Deptford, Kent. The first recorded spelling of the family name is shown to be that of Alice Gogun, which was dated 1273, in the "Hundred Rolls of Oxfordshire", during the reign of King Edward 1, known as "The Hammer of the Scots", 1272 - 1307. 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.