William Comyn, jure uxoris Earl of Buchan

William Comyn
Map of Scotland, showing the area of Buchan which Comyn ruled over, on the north-east coast, c.1230.
Sheriff of Forfar
In office 1195–1211
Justiciar of Scotia
In office 1205–1233
Preceded by	Gille Brigte, Earl of Strathearn
Succeeded by	Walter Stewart, 3rd High Steward of Scotland
Warden of Moray / Guardian of Moray
In office 1211–1212
Personal details
Born	c.1163 Altyre, Moray
Died	1233 Buchan, Aberdeenshire
Spouse(s)	Sarah Fitzhugh (1193–1204); Marjory, Countess of Buchan (1212–death)
Children	est. 13 (see family tree at bottom)

William Comyn was Lord of Badenoch and Earl of Buchan. He was one of the seven children of Richard Comyn, Justiciar of Lothian, and Hextilda of Tynedale. He was born in Scotland, in Altyre, Moray in 1163 and died in Buchan in 1233 where he is buried in Deer Abbey.

William made his fortune in the service of king William I of Scotland fighting the Meic Uilleim in the north. William witnesses no less than 88 charters of the king. William was sheriff of Forfar (1195–1211), Justiciar of Scotia (1205–33) and warden of Moray (1211–2). Between 1199 and 1200, William was sent to England to discuss important matters on King William's behalf with the new king, John.

William was appointed to the prestigious office of Justiciar of Scotia, the most senior royal office in the kingdom, in 1205. Between 1211 and 1212, William, as Warden of Moray (or Guardian of Moray) fought against the insurgency of Gofraid mac Domnaill (of the Meic Uilleim family), who William beheaded in Kincardine in 1213. Upon finally destroying the Meic Uilleim's in 1229, he was given the Lordship of Badenoch and the lands it controlled.

From an unknown date, William held the title Lord of Kilbride.

He helped oversee the construction of St Mungo's Cathedral in Glasgow and after his death, Marjory continued his work there.

During his period as Warden of Moray, Comyn was so successful, it may have been the reason he received the hand of Marjory (a.k.a. Margaret), Countess of Buchan, sometime between 1209-1212. Her father Fergus, Earl of Buchan, had no male heirs and so in marrying his daughter to William he ensured a suitable line for his titles before his death. Dying sometime around 1214 (perhaps earlier) William took over the management of the mormaerdom (earldom) of Bucham, by right of his wife.