Duncan I was a King of Scotland who reigned from 1034 to 1040. He was the grandson of Malcolm II and belonged to the House of Dunkeld. His rule is often noted for its attempts to consolidate power and maintain peace in a time of regional conflicts. Duncan I is best known for his portrayal in William Shakespeare's play "Macbeth," where he is depicted as a virtuous king. His reign ended when he was defeated and killed by Macbeth, who was a nobleman and his cousin, leading to a significant shift in Scottish history.