About 1382 Sir Alexander Stewart (died circa 1404), "the wolf of Badenoch", a son of King Robert II, became earl of Buchan, and the Stewartss appear to have held the earldom for about a century and a half, although not in a direct line from Sir Alexander. Among the most celebrated of the Stewart earls were the Scottish regent, Robert, duke of Albany, and his son John Stewart, who became a constable of France and was killed at the Battle of Verneuil in 1424.
In 1617 the earldom came to James Erskine (died 1640), a son of John Erskine, 2nd or 7th Earl of Mar, whose wife Mary had inherited it from her father, James Douglas (died 1601); and from that time the Erskines have retained the title.
Perhaps the most celebrated of the later earls of Buchan was the eccentric David Steuart Erskine, 11th earl (1742 - 1829), a son of Henry David, 10th earl (died 1767), and brother of Henry Erskine (1746 - 1817) and of Thomas, Lord Erskine. His pertinacity helped in effecting a change in the method of electing Scottish representative peers, and in 1780 he succeeded in founding the Scottish Society of Antiquaries. His correspondents included Horace Walpole, and he wrote an Essay on the Lives of Fletcher of Saltoun and the Poet Thomson (1792), and other writings. He died at his residence at Dryburgh in April 1829, leaving no legitimate children, and the earldom passed to his nephew Henry David (1783 - 1857), the 12th earl.
The 11th earl's natural son, Sir David Erskine (1772 - 1837), who inherited his father's unentailed estates, worked as an antiquary and a dramatist.
Original text from the 1911 Encyclopaedia Britannica