Causantín, Mormaer of Fife

or Constantine of Fife is the first man known for certain to have been mormaer (earl) of Fife, having this authority no later than 1107.

Ancestry Very little is known about 's life and reign as mormaer of Fife. His father, for instance, is not known by name. He may have been the son or grandson of the who gave rise to William Shakespeare's character Macduff; the latter being the son of , son of or Kenneth III, king of Alba (997–1005). His role as a senior lawman makes it likely that he spent some time in his early life at a native Scottish law school, but this is simply reasoned conjecture.

Historical significance 's first appearance in history is a charter dated to 1095 when he appears as . The historian John Bannerman has suggested that this represents a translation of . Here, means 'grandson of' or more loosely 'descendant of', in the same way that the Irish used or . The formula has also been shown in Ireland. The Annals of Ulster (s.a. 1028), for instance, used this formula where they would later use . If Bannerman's suggestion is correct, the charter is calling the "descendant of Dub" rather than a son of a man with the name MacDuib (= Clan MacDuff). Similar examples can, again, be seen for the more extensive evidence offered by contemporary Ireland. For example, the Annals of Ulster style , son of , as , but it was 's grandfather (and 's father) who was named . By comparison, the Annals of Innisfallen call the same man . Staying in Ireland, the kings of call themselves . One is named ; This very same kindred were also known in Annals of Ulster as the .

Offices held In 1128, in the fourth year of the reign of King David I of Scotland, appears as , "High " of Scotland north of the River Forth, an office held to be the Gaelic precursor to what would become the Justiciarship of Scotia. In this role, he appears alongside the (judge) (Maldoven son of Macbeth) as arbitrator in a land dispute between a knight called Robert of Burgon (Robert the Burgundian, who owned the estate of Lochore, which bordered the disputed territory), and the of St Serf's Inch. In this case, both and chose to defer to the superior legal wisdom of another. appears in a charter of King David's, dated 1126, giving confirmation of the rights of Dunfermline Priory and promoting it to abbey status. His name occurs as a witness, alongside bishops John of Glasgow, Robert of St Andrews, Cormac of Dunkeld, Gregoir of Moray, of Rosemarkie, and mormaers of Strathearn, of Mar, of Atholl, and 's kinsman and eventual successor , Chief of (Clan MacDuff), among others. appears to have gotten involved in several disputes with the said monastery, and he is alleged to have withheld lands around Kirkcaldy which had been granted to the monastery.

appears to have died by 1130, when another member of the kindred, the who appeared alongside him in the charter of 1126, was ruling as mormaer; although the latter may have been using the title (mormaer) as early as 1126, and had been using the style since at least 1126. (Duncan) I, who succeeded , may have been 's son.