The MacMillans are one of the oldest clans in Scotland, being descended from a 12th century religious devotee called Gilchrist, who was a son of Cormac bishop of Dunkeld - a great-great-grandson of the 11th century Scots king Macbeth. The collective name of Gilchrist’s descendants, Clann an Mhaoil or “Children of the Tonsured One”, comes from the nickname by which he is remembered: Maolan, “Tonsured-One” / An Gillemaol, “Tonsured Servant (of God)”. The two resulting surnames, MacMhaolain and MacGhillemhaoil, have been transcribed phonetically by Scots and English speaking people in over 200 different ways over the centuries; so there is no “correct” English version, though the majority of modern clan members use variations on the three most usual forms: Macmillan, MacMillan, McMillan. To find out more go to http://www.clanmacmillan.org/Introduction.htm
**This was copied from the website, clanmacmillan.org**