MacNeill A surname of Scottish origin, the MacNeillís of Barra (an island of the Outer Hebrides), who were followers of the Lord of the Isles came to Ireland as galloglasses during the fourteenth century. The later became lords of Clandeboy. Subsequently MacNeillís came to north Antrim in the late sixteenth centuy. In 1890 McNeill was principally found in Antrim and Derry, and the estimated number of bearers was 2,600. In the United States McNeil is the 811th most numerous surname with an estimated 41,250 bearers, and McNiel is the 9,212th most numerous surname with an estimated 2,750 bearers.