Recorded in a wide range of spellings including: Gilfillan, Gilffillan, Gilfillan, Gillffilland, Gillilan, Gilliland, and no doubt others, this is a Scottish surname, but widely prevalent in its different spllings in the province of Ulster, Northern Ireland. It derives from the pre 10th century Gaelic name "Mac gille Fhaolain", meaning "The son of the servant of St. Faolan", an early saint whose personal name represents a diminutive form of "faol", meaning wolf. This personal name appears frequently in the early charters and registers of Scotland from the 12th Century, and examples taken from surviving charters include: Gillefalyn who held land in Lauderdale in the year 1214, whilst Gilfelan MacGuostuf witnessed a charter by Maldoune, 3rd Early of Levenax, in 1217, and a Gillifelan is recorded as being dean of Kintyre in 1250. The surname is much later and examples include: Ewan Gillfillance, in the register of the Privvy Seal of Scotland in 1516, and James Guilliland was christened on July 8th 1743 at Hand Alley and New Broad Street, Presbyterian, London. The first recorded spelling of the family name is believed to be that of Duncan M'Gillauenan, given as being a chief in the lineage of Clenafren in the year 1298. This was in the period of the Republican Government of Scotland, 1296 - 1306. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.