Recorded in a variety of spellings including Kilgannon, Kilgallen, Kilgallon and Kilcullen, this is an Irish surname, and specifically from Counties Mayo and Sligo in the far west. Formerly prefixed with the Gaelic 'Mac' meaning son of, the surname is now only found in its shortened form. It probably 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. It is said that the spelling as Kilgannon, 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 destroyed the Public Records Office in Dublin. This was not an act against the British, but during the Civil War of 1922 - 1924. Early examples of the surname recording taken from surviving registers include: Andreas Kilgallen, at Drumcliff, County Sligo, on June 12th 1848, whilst on June 11th 1865 the same man is recorded as Andre Kilgallon, when he married Brigid Feeny, also at Drumcliff. Another recording from the same period is that of William Kilgannon or Kilgammon, it being recorded both ways, who left Ireland on the ship "Sea of New York" bound for New York on March 23rd 1847.