A Scottish nobleman, Thane of Fife.
He has a family, including Lady Macduff and two young sons.
Macduff is the foil and rival of Macbeth, ultimately taking Macbeth off the throne by force.
Macduff ventures to find Malcom, the rightful King, after the murder of King Duncan and helps to raise an army so that Scotland may have a better, more righteous ruler than the violent and deceitful Macbeth. After Macbeth has his family murdered, his motivation increases and he takes on Macbeth in single combat, cutting off his head.
The witch's prophecy allowed him to kill Macbeth as it says 'none born of a woman shall harm Macbeth', and Macduff was in fact delivered to the world via cesarean section.