Answer:
King Duncan I.
Explanation:
Macbeth, also known as the "Red King" was the king of the Scots from 1040 till his death. He succeeded King Duncan I who was killed during the war against the Moray, the family of Macbeth.
Macbeth is from the Moray line of family, and may have been the grandson of Malcolm III. He became the Mormaer of Moray in 1032 and may have also been responsible for the death of the previous Mormaer. He ruled over the Scotish kingdom till his death in 1057.
Macbeth is also the name of one of William Shakespeare's famous play with the character title. But historians and scholars refuted the similarity of the two Macbeths. Macbeth, the man is quite different from the fictional Macbeth as presented by Shakespeare. The fictional Macbeth is shown as manipulative and selfish, murdering anyone to be king. This hasn't been found to be true of the real life Macbeth.
Even the deaths of the two Macbeths are different. In the story, Macbeth was killed by Macduff, a nobleman after Macduff asked Malcolm, Duncan's son, to return to Scotland and become king. Whereas, in realty, Malcolm had fled to England after Macbeth murdered his father, King Duncan. He became the protege of Edward, the Confessor. Edward then sent Malcolm to take back Scotland from Macbeth, thus resulting in a fight. But Macbeth is not killed in the war. And there is no record of him dying during the fight, which contrasts the play's story. The two met again in another war, the Battle of Lumphanan. Here, Macbeth was gravely injured and died on August 15, 1057, succeeded by his step-son Lulach, who will eventually be killed by Malcolm.
