The Mormaer or Earl of Ross refers to the leader of a medieval Gaelic lordship in northern Scotland, roughly between the Oykell and the Beauly. Initially, it was probably confined entirely to Easter Ross to an area between the Dornoch Firth and the Cromarty Firth, i.e. the Tarbat peninsula and the parishes of Kiltearn (equal to the modern Evanton) and Alness. The earliest man we known of to have the comital title to Ross, was the rebel Máel Coluim mac Áeda. However, the true founder was of course the famous Ferchar mac in tSagairt, who attained the title probably sometime in the 1220s by destroying the "MacHeths" and "Meic Uilleim", two rebel kinship groups.
His son and successor Uilleam I greatly expanded the Mormaerdom, conquering territory from the Kingdom of Norway. The line ended in 1372, when Uilleam III died with no heir, and his daughter Euphemia married Walter Lesley. The comital Lordship eventually passed into the hands of the MacDonald Lords of the Isles.
The role of Chief of Clan Ross was with the earls of Ross until Uilleam III, Earl of Ross died in 1372. It then passed to Euphemia I, Countess of Ross, who became the wife of Sir Walter Leslie. The position of Earl of Ross stayed with the Leslie line until the death of Alexander Leslie, Earl of Ross in 1402. The Earldom then passed to MacDonald, Lord of the Isles and then later it passed to the House of Stewart. From then onwards the chieftenship of Clan Ross fell to aline descended from Aodh, Earl of Ross (d. 1334). The title remained in crown hands until, on January 23, 1481, it was awarded to James Stewart, the second son of James III, King of Scots. He was simultaneously created Lord Ardmannoch and Lord Brechin and Navar. He was later created Duke of Ross. The fourth creation was on May 20, 1565, for Henry Stuart, Lord Darnley, who was simultaneously created Lord Ardmannoch. Shortly thereafter (July 20, 1565) he was created Duke of Albany. After his murder at Kirk o' Field House, he was succeeded by his infant son James, whose accession as James VI a few months later returned the peerages to the crown. Upon the creation of Charles Stuart as Duke of Albany on January 23, 1600, he was also invested with the subsidiary titles of Marquess of Ormonde, Earl of Ross, and Lord Ardmannoch. He was crowned as Charles I in 1625, and the titles again returned to the crown.
However, Brown (1834) states: "Earl of Ross (Extinct) was claimed in 1778 by Munro Ross of Pitcalnie, as male descendant of Hugh Ross of Rarichus, brother of the last Earl."