HIGHLANDERS, A HISTORY OF THE SCOTTISH CLANS, by Fitzroy MacLean, Penguin Studio Books, New York, N.Y. (1995), p. 256 says this about the origin of the Gordon Clan.
"The name Gordon is derived from the Parish of Gordon in Berwickshire.
The Gordons are of Norman origin and settled in the South of Scotland in the 12th Century. In the early 14th century Sir Adam de Gordon was granted lands in Strathbogie in Aberdeenshire by King Robert the Bruce. In 1449 Alexander Gordon was created Earl of Huntly. George, 4th Earl of Huntly became Chancellor of Scotland in 1547. George (6th Earl of Huntly) who defeated Argyll at the Battle of Glenlivet was created Marquess in 1599. The 2nd Marquess, a loyal supporter of Charles I, was beheaded in 1649. In 1684 George, the 4th Marquess, was created Duke of Gordon by King Charles II. In the Jacobite Risings of 1715 and 1745 the Gordons fought on both sides. The 2nd Duke was out for the Jacobites in 1715. In 1745 the 3rd Duke supported the Hanoverians, though his brother raised a regiment for Prince Charles. The Gordon Highlanders were raised in 1794 with the help of the celebrated 4th Duchess."
Margaret McCleskey Arlington TX
HISTORY OF THE HOUSE OF GORDON
"...In the year 1040, Duncan I., King of Scotland was defeated and slain near Elgin by Maclbeatha (Shakespear's Macbeth)...The son of Duncan, Malcolm Canmore fled to England and was received at the court of Edward the Confessor where he lived for some fifteen years.....one of the most powerful lords, Duff, Thane of Fife, went to England and persuaded Malcolm to make an effort to regain the throne. Edward the Confessor granted Malcolm the aid of some ten thousand men under Siefried, Earl of Northumberland, and with these and some French and Norman knights then at the English Court, Malcolm marched into Scotland. Eventually he met Maclbeatha at Lumphanan, some twenty miles west of Aberdeen, when the usurper was defeated and slain in 1057. It was in this manner that the Gordons first came into Scotland, for among the foreign knights who accompanied Malcolm was ADAM DE GORDUN who, for his services in aiding Malcolm to regain the throne, was granted lands near the lower Tweed, and these lands were called Gordon after his name. We hear no more of Adam till 1093 when Malcolm Canmore invaded England and was defeated and killed near Alnwick. Among the slain was Adam who left a son - Adam de Gordun II.