Recorded in a variety of spellings including Kilgallen, Kilgallon and Kilcullen, this is an Irish surname. Formerly prefixed with the Gaelic 'Mac' meaning 'son of', the surname is now only found in its shortened form. It originates from the pre 10th century 'Mac Giolla Chaillin' which translates as 'the follower of St Cailin', a popular figure in the country from the early days of Christianity. The surname as Kilgallen and Kilgallon is most often recorded in County Sligo, although across the county border into Mayo, the spelling is more usually Kilcullen. Although it is probable that the surname was first recorded as early as the 14th century, sadly the early charters and registers of the country, which may have given proof to this statement, were totally lost in 1922, when the IRA in a fit of vandalism, destroyed the Public Records Office in Dublin. This was not an act against the British, but during the Civil War of 1922 - 1924, when then as now, they preferred force to democratic discussion and the rule of law. Early examples of the surname recording taken from surviving registers include: Andreas Kilgallen, at Drumcliff, County Sligo, on June 12th 1648, whilst on June 11th 1865 the same man is recorded as Andre Kilgallon, when he married Brigidae Feeny, also at Drumcliff. Another recording from the same period is that of John Kilcullen, who married Mary Clarke at Skreen, County Mayo, on October 20th 1865.