Máel Coluim mac Domnaill (anglicised Malcolm I) was king of Scots (before 943 – 954), becoming king when his cousin Causantín mac Áeda abdicated to become a monk. He was the son of Domnall mac Causantín.
Since his father was known to have died in the year 900, Malcolm must have been born no later than 901. By the 940s, he was no longer a young man, and may have become impatient in awaiting the throne. Willingly or not—the 11th-century Prophecy of Berchán, a verse history in the form of a supposed prophecy, states that it was not a voluntary decision that Constantine II abdicated in 943 and entered a monastery, leaving the kingdom to Malcolm.
In 945, Edmund I of England, having expelled Amlaíb Cuaran (Olaf Sihtricsson) from Northumbria, devastated Cumbria and blinded two sons of Domnall mac Eógain, king of Strathclyde. It is said that he then "let" or "commended" Strathclyde to Máel Coluim in return for an alliance. What is to be understood by "let" or "commended" is unclear, but it may well mean that Máel Coluim had been the overlord of Strathclyde and that Edmund recognised this while taking lands in southern Cumbria for himself.
The Chronicle of the Kings of Alba says that Máel Coluim took an army into Moray "and slew Cellach". Cellach is not named in the surviving genealogies of the rulers of Moray, and his identity is unknown.
Máel Coluim appears to have kept his agreement with the late English king, which may have been renewed with the new king, Edmund having been murdered in 946 and succeeded by his brother Edred. Eric Bloodaxe took York in 948, before being driven out by Edred, and when Amlaíb Cuaran again took York in 949–950, Máel Coluim raided Northumbria as far south as the Tees taking "a multitude of people and many herds of cattle" according to the Chronicle. The Annals of Ulster for 952 report a battle between "the men of Alba and the Britons [of Strathclyde] and the English" against the foreigners, i.e. the Northmen or the Norse-Gaels. This battle is not reported by the Anglo-Saxon Chronicle, and it is unclear whether it should be related to the expulsion of Amlaíb Cuaran from York or the return of Eric Bloodaxe.
The Annals of Ulster report that Máel Coluim was killed in 954. Other sources place this most probably in the Mearns, either at Fetteresso following the Chronicle, or at Dunnottar following the Prophecy of Berchán. He was buried on Iona. Máel Coluim's sons Dub and Cináed were later kings.