This name, with variant spellings Scanlon, O' Scandall, O' Scannill, (O') Scanlan, and (O') Scanlon, is an anglicized form of the Olde Gaelic O Scannlain. The Gaelic prefix 'O' indicates 'male descendant of', the personal byname Scannlain from 'Scannal' meaning 'contention'. Two distinct septs whose descendants are now known as Scanlon existed in Ireland. One, having the rare prefix 'mac' i.e. Mac Scannlain, held territory in County Louth and gave their name to Ballymascanlon near Dundalk. The name is seldom if ever found in its place of origin now. The second main sept belonged to West Munster, (Counties Cork, Kerry, Limerick, and Clare) and the 1659 'census' shows a high incidence of births in this area. Ballyscanlan in County Clare derived its name from the sept. Another important branch settled in County Sligo and appears as O' Scannell and O' Scanlon in the 1585 'Composition Book of Connacht'. The first recorded spelling of the family name is shown to be that of Most Reverend Patrick O' Scanlan (also called O' Scannell), which was dated 1262 - 1272, Bishop of Raphoe and afterwards of Armagh, during the reign of De Brugo, a Norman Conqueror circa 1260 - 1265. 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.