The name Mackay is believed to have originated as MacEth. It comes from the sons of Ethelred, who was the 4th son of King Malcolm and Margaret around 1080. Ethelred moved to the Highlands and desired a more Celtic name and thus changed it to Eth which was pronounced very similarly to the Celtic name Aed. His children were MacEth's and the name eventually changed to MacKay.
Why bother doing any research into the "First Earl of Ross"? We could simply blame the bad handwriting of some early, ill-informed scribes ... or, as in the case of William Forbes Skene, we might ignore him completely by declaring Malcolm to be a myth. Unfortunately, some historians have chosen to explore no further!
There is no intent here to cast aspersion upon statements by respected historians. On certain issues, I must make choices when logic compels me to do so. Perhaps I can clarify my reasons for leaning towards contributions from the clans who were immediate neighbours of the Rosses.
Let us begin with THE SCOTTISH HISTORICAL REVIEW, Vol. XVII & XVIII, 1920-1921, p. 155, where the following article may be located.
"MACBETH, MACHETH (S.H.R. xvii. 155, 338). These two names may be two latin (English) renderings of the same Gaelic name M'Bheatha, 'Son of Life', a personal name originally, not patronymic. MacKay is the English form of Gealic M'Aoidh, from Aoidh, fire. (See Macbain's Gaelic Dictionary.) In support of the above suggestion may be quoted Lawrie's Early Scottish Charters. Maledoun is referred to as Macocbeth (p. 63, 1128), Machedath (p. 67, 1128), MacBead (p. 78, 1131-1132). MacTurfin is mentioned as Macbet (p.120, 1143), Machet (p. 166, 1150) and Macbeth (p. 171 & p. 195, 1150) . The Gaelic name M'Bheatha was thus rendered in Latin (and English) as MacBeth and MacHeth, one letter of the aspirate B (B H) being used in each case. A. W. Johnston, Chelsea, S.W. "
On the same page, but in the preceding article "MacBeth or MacHeth", John MacBeth states, "Then as to Malcolm MacBeth. According to J. Stevenson's translation of the Chron. Of Holyrood under date 1157 Malcolm's name is given as Malcolm Machel - a son of fire truly. Of course if the Macheths can be changed into MacKays they must be 'sons of fire', but they have a better heritage among the Macbeths, their real kindred."
Conclusions must be drawn from and credited to one's sources, assistant-researchers or collaborators. I offer a quotation from the definitive history of The Great Clan Ross by Dr. John Robert Ross. On page 43 (op.cit.), he writes, "The previous Earl of Ross is recognized with much justification by some authorities, namely Malcolm MacAedth who held the Earldom from 1153 to 1168. This abbot was placed in charge of the Monks of Dunfermline and created Earl of Ross by a royal mandate from Malcolm King of Scots in 1153 but very little is known of him other than this. He is said to have married a sister of King Somerled of the Isles."
Rosalind Mitchison (Op.cit., p. 28) allows that "in Argyll there reigned Somerled, almost independent, a semi-king" until he was killed in 1164 by Malcolm IV. Prebble (Op.cit., p.52) wrote that Someled was the father-in-law of Donald "MacHeth", whom we have identified as the son of Malcolm Macbeth. After the 1160 treaty between Malcolm IV and Somerled, Frank Adam (Op.cit., p. 18 - 19) notes, "The Crown and Somerled seem to have agreed that the MacHeth line be transferred to the remotest corner of Scotland - Strathnaver." Upon the death of Malcolm Macbeth in 1168, the inheritance of the title to the Earldom of Ross was most likely passed in the Pictish mode through a Countess of Ross (of whom there would be quite a number during the history of the Earldom).
The debate may continue on about MacBeth/MacHeth/Macbeth/Macheth or M'Aoidh/MacAedth/MacAed for many years to come. There is no dispute about the year when Clan Ross was raised in status from the paired district of Moray and Ross - 1160. There are few who dispute that the successor of Malcolm was the second Earl of Ross. It is, however, most significant that the FRASER CHRONICLES (and others) gave us his full name - Malcolm Macbeth.