Duncan I was known as Donnchad mac Crínáin in the Gaelic. Duncan was possibly married to a woman named, Suthen, and they had at least two sons, Malcolm III and Donald. Upon the death of his grandfather, Malcolm II, on November 25, 1034, Duncan became King of Scotland. In 1040, he led an army north to Moray where he was killed in action on August 14, by Macbeth. Macbeth then became king and reigned until Malcolm III killed him.
*This is the King Duncan, William Shakespeare on which based his famous play, Macbeth. However, the real Duncan was still a young man at the time of his death.