Alexander Comyn, 2nd Earl of Buchan (died 1289) was a Scoto-Norman magnate who was one of the most important figures in the 13th century Kingdom of Scotland. He was the son of William Comyn, jure uxoris Earl of Buchan, and Marjory, Countess of Buchan, the heiress of the last native Scottish Mormaer of Buchan, Fergus. He was the chief counsellor of Alexander III, King of Scots for the entire period of the king's majority and, as Scotland's leading magnate, played a key role in safeguarding the independence of the Scottish monarchy. During his long career, Alexander Comyn was Justiciar of Scotia (1258–89), Constable of Scotland (1275–89),^[1] Sheriff of Wigtown (1263–66), Sheriff of Dingwall (1264–66), Ballie of Inverie (in Knoydart) and finally, Guardian of Scotland (1286–89) during the first interregnum following the death of Alexander III. In 1284 he joined with other Scottish noblemen who acknowledged Margaret of Norway as the heiress to King Alexander.^[2] He died sometime after 10 July 1289.

Alexander Comyn, 2nd Earl Buchan
Coat of arms as Earl of Buchan.
Guardian of Scotland
In office 1286–1289
Preceded by	Duncan Macduff
Succeeded by	James Stewart
Justiciar of Scotia
In office 1258–1289
Preceded by	Alan Durward
Succeeded by	Andreas de Moravia
Constable of Scotland
In office 1275–1289
Preceded by	Marjory Countess of Buchan
Succeeded by	John Comyn
Personal details
Born	Unknown (circa 1218) Buchan, Aberdeenshire
Died	Unknown (late 1289) Northern Scotland
Spouse	Elizabeth de Quincy
Children	Roger, Marjorie, Elisabetha, William, Emma, John, Elena
Parent(s)	William Comyn, Lord of Badenoch Marjory, Countess of Buchan
Occupation	Sheriff, baillie
Also served as Sheriff of Wigtown and Dingwall and Baillie of Inverie. Dates of rule unknown.

Alexander had at least nine children with his wife, Elizabeth, daughter of Roger de Quincy, 2nd Earl of Winchester:

• John Comyn, 3rd Earl of Buchan, Alexander's successor as Earl of Buchan
• Roger
• Lord Alexander Comyn, sheriff of Aberdeen, married Joan, sister of William le Latimer, and had issue. Henry de Beaumont would claim the Earldom of Buchan through marriage to their daughter, Alice.
• Lord William Comyn, Provost of St. Mary's Church, St. Andrews
• Lady Marjorie Comyn, m. Patrick Dunbar, 8th Earl of Dunbar
• Lady Agnes Egidia Comyn, m. Maol Íosa III, Earl of Strathearn
• Lady Elisabetha Comyn, m. Gilbert de Umfraville, 1st Earl of Angus
• Lady Elena Comyn, m. Sir William de Brechin
• Lady Annora Comyn, m. Nicholas de Soules