Recorded in many spellings including Mangan, Mangham, Mangam, Mangin, Mangum, Mangon, Mingame, Mongan, Mongain, Mongin, Mungan, Mungane, Mungin and others, this is an Irish medieval surname. It derives from the ancient and possibly pre 10th century Gaelic name O' Mongain meaning 'The male descendant of Mongan'. The latter was a nickname for the original chief of the clan, who presumably had a particularly luxurious or wild growth of hair. Many, perhaps the majority of Irish Gaelic surnames were nicknames for the original chief or leader, and this is a good example. The derivation is 'mong', meaning long-haired. Three branches of this clan originally existed in ancient Ireland. These were a sept in Ulster which gave its name to the parish of Termonomongan in County Tyrone, whilst the second was orginally based upon Counties Cork and Tipperary, whilst the third sept lay in North Connacht. Space only allows for a few early recordings but these include Teag Managan, in the Hearth Tax rolls of 1665 for County Tipperary, and Patritii Mongan and Mariae Flanagan, who were married Kilbride in County Roscommon in 1845. Surnames generally became necessary when governments introduced personal taxation. In some parts of the British Isles, this was 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.