Its Roots in Gaeldom
On the east side of Gigha's Kilchattan Church lies this figure of a warrior. The islanders called it "Malcolm's Grave." It probably marks the grave of Malcolm McNeill, a fifteenth century chieftain. According to Czerkawska, on pages 104 and 105,
When the Lords of the Isles resigned Kintyre and Knapdale, Malcolm is found in possession of Gigha.... he died in 1493...
The McNeills are certainly an old and established clan. However, a lot happened with the rise and fall various dynasties, to the point where there is disagreement as to McNeill lineage. In fact, there are some who argue that the present Clan McNeill is actually an offshoot of the Clan McLean. Somerled McMillan, in his Families of Knapdale, concludes that Clan McNeill in Knapdale is descended from the McLeans (see page 22.)This argument is beyond my ken, so I am herewith providing you with an article outlining a counter argument. (Click on the red and blue thumbnail for access to this essay.)
The following table is derived from that excellent source, The Highland Clans, by Sir Iain Moncreiffe of that Ilk, Albany Herald, Bramhall House, 1977. The lineages have been very simplified for this website.