Born around 1078, fourth son of Malcolm III Canmore, Alexander III succeeded his brother Edgar the Peaceable on the Scottish throne, in 1107. His mother was Margaret, daughter of Edward Atheling, son of Edmund Ironside.
By Edgar's instructions, however, the entire southern districts, south of the Forth-Clyde divide, were created an earldom for another of his brothers, David, and Alexander was unsuccessful in obtaining these lands for his own rule.
History records Alexander as a militant warrior and a pious churchman, founding several bishoprics and abbeys, including those of Scone and Inchcolm (which led to quarrels with the English metropolitan sees, who re greater Scots ecclesiastical independence). At the same time Alexander relentlessly searched out the last remnants of the House of Atholl, extirpating any he found, as a means of preventing insurrections. He also supported Henry I's efforts to subjugate Wales in 1114, leading troops to assist in the campaign.
He married Sybilla, natural daughter of the English king, Henry I, in the same year as he took the throne, but their marriage was childess and she died in 1122.
Alexander died in 1124 and was succeeded by his brother David.
He was named for the Pope, Alexander II. Post mortem, he received the by-name "The Fierce".