Macduff's Son is from Macbeth. He, obviously, is the son of Macduff (he was never given a real name). He is probably around 7 to 10 years old in the play. During his only appearance in Act IV, Scene ii, he is told by his mother that his father is dead. He doesn't believe her and says that if Macduff were really dead, she'd cry for him, and if she didn't then it would "be a good sign that I [the boy] should quickly have a new father."
The two begin to joke with each other, but suddenly a messenger arrives, telling the boy's mother that she should quickly get out of the castle with her children, because they're in terrible danger.
But it's too late. The three murderers arrive. When they say that Macduff was a traitor, the boy bravely leaps forward and defends his father. Sadly, upon doing this, one of the murderers stabs him. Before he dies however, he tells his mother to run away.