Then he is dead?

          Macbeth has died, true, but his death occurred long before he was beheaded by Macduff. I believe Macbeth died the second he killed Duncan. Throughout the play he gradually becomes more malicious and insane and I feel it is because he had completely lost himself after the incident. Obviously you could tell that  Macbeth was not this kind of person on a normal basis, but with a little bit of persuasion from his wife and a bit of desire for power, he became a man no one suspected. The real Macbeth had died and he had lost his mind. He went on to kill anyone who threatened his role of king and that got him into a lot of consequences. He and his wife begin seeing things and go crazy which showed that they had really been pushed off the edge. Macbeth's reality dies long before Macduff had enough and took it into his own hand to killed him. So yes, Macbeth is dead, but first mentally, then physically.