Donald II of Scotland

Donald II (c. 862–900), son of Constantine I, took power in 889 after the fall of Giric, who had killed his uncle Áed, and was nicknamed Dásachtach, ‘the Madman’. Irish annals style him king of Alba, not king of the Picts.

He spent his reign fighting Vikings: he defeated the Danes at Innisibsolian, then died at Norse hands when Dunnottar was sacked in 900. He was succeeded by his cousin Constantine II; his son later reigned as Malcolm I.