The more common Scottish spelling of the name is Maclellan... The following information was taken from
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Clan MacLellan
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This name translates as the son of the gillie, or servant of St. Fillan. Fillan is a reduced form of "faelchu", Old Irish for wolf. MacLellans were numerous in Galloway in the later half of the 14th Century and they gave their name to Balmaclellan, MacLellan's town, in the Stewartry of Galloway. It is said that these lands were given to John MacLellan by James III in 1466 on John MacLellan's bestowing a site for a church on them. The chiefly family descends from the MacLellans of Bombie, the title Lord Kirkcudbight being conferred on Sir Robert MacLellan in 1633 ; he died in 1641 leaving only a daughter and as the barony was only heritable by a male heir bearing the family's names and arms he was succeeded by a nephew. The second Lord Kircudbright died without any children and the title and lands were passed on to a cousin. The 3rd Lord was a zealous Royalist and forced his vassals to take up arms in the cause of the King, during the course of which the villages of Dunrod and Galtway were ruined. However, his ardour seemed to cool somewahat after the Restoration and he sanctioned a riot by the people of Kircudbright to prevent an Episcopalian minister taking over the church in the town. He died, greatly in debt, in 1664 and his son, by right the 4th Lord died without having fathered children in 1669. The estate had been seized and sold by creditors ; the title was reclaimed in 1736 when James MacLellan petitioned the King on the matter, and passed on through to the 9th Lord when it became dormant on his death in 1832. A story is told of how the MacLellans got their unusual crest. Sir Patrick MacLellan was forced to forfeit his lands and some years later James II offered the barony to anyone who could clear the country of a band of marauding band of gypsies. Sir William MacLellan, whose father had been the proprietor of the lands, carried out the task and to prove this he carried the severed head of one of the gypsies on the point of his sword when he went to claim his prize from the King.
Thanks to James Pringle Weavers for the following information
MACLELLAN/ MACCLELLAN etc: The name is derived from "Mac Gille Fhaolain"(son of the servant or devotee of St. Fillan), and, as more than one Saint so named appears in the Calendars - each associated with different parts of Scotland, it is probable that more than one line of devotees evolved. The name Maclellan is principally associated with Kirkcudbright and Galloway and is found there from an early date. Sir John (Maclellan) de Bondeby, who was with Wallace at Falkirk in 1298, also appears in the Ragman Rolls, and a Gilbert Maclellan, was Bishop of Man and the Sudreys in 1321. The Maclellans were hereditary sheriffs of Kirkcudbright and Galloway prior to the Agnews, and possessed great wealth and influence, but after the murder of Sir Patrick Maclellan by the Black Earl of Douglas at Threave in 1452, their reprisals without the King's approval caused forfeiture of their Barony of Bomby, and several collateral estates. In 1455 some estates were recovered, when James II, with assistance from Maclellans, and the great bombard 'Mons Meg', undertook the victorious seige of Threave Castle. During the Border Wars and Reformation in the 1500s, many left Galloway for other parts of Scotland, and Ulster. Although Sir Robert Maclellan of Bomby was created Lord Kirkcudbright by Charles I in 1633, the two ensuing Lords were Covenanters who both raised regiments in Galloway against the king. John, the 3rd Lord, an eccentric man who fell heavily into debt, lost his lands, and when he died, his young heir who died five years later in 1669, was succeeded by a cousin who did not take up the title. The Lordship was contested between c.1720 - 1742, during which time two separate people voted as 'Kirkcudbright' in the same elections of representative peers. The 7th Lord petitioned the king and had his claim allowed by the House of Lords in 1773 - the title continuing down to the 10th Lord, since when it has remained dormant. His daughter died without issue in 1874. A distinct race were also known in Perthshire, and these are associated with the Macnabs, who trace descent from the hereditary abbots of Strathfillan.