Tyranny refers to a type of centralized government where there are no limitations on an individual's display of power. The lack of institutional checks to the exercise of one's political power can lead to tyranny, which usually implies the abuse of one's power. Macbeth is certainly a solitary ruler, in that his assumption of power is one that is done without any other institutional checks or limitations. The tyrant aspect is present in that he seeks to appropriate his own political world in accordance to his own subjectivity. His exercise of power is not done through a participatory manner, as it is one where he covets and assumes control based on what he covets. There are many parallels between this exercise of power and Hitler's in the 1930s, post World War I. Hitler did not seek to assume his power through a legitimate discourse. Rather, he sought to eradicate all checks to his power in consolidation of control and the exercise of his own appropriation of his conception of the good.
I agree with the previous post that Macbeth may be a tyrant, but he cannot be compared with any 20th century tyrannical ruler.
'Tyrant' is from the Latin 'tyrannus', meaning an 'illegitimate ruler'. The rule of such a ruler is tyranny. Macbeth is called a 'tyrant' ever since the Banquet scene that must have exposed his murderous venture to the throne of Scotland. He reportedly unleashed a despotic and coercive rule, wholesale murders and conspiracies being the order of the day. Macbeth was an illegitimate ruler who used power in the most unethical and horrid manner to enforce legitimacy.
But, at same time, Macbeth suffered a lot deep within himself; he dwindled, hesitated, got frightened, invited his own doom, lost his head fighting Macduff. He was punished with sleeplessness, and pushed to veritable madness.
Macbeth, a Renaissance re-construction of the 11th century feudal lord, cannot be compared to the Nazi ruler of Germany, Hitler, or for that matter, the Soviet Socialist chief, Stalin. Furthermore, Macbeth is a dramatic chracter, very different and far more complex compared to any of modern day tyrants.
Macbeth can not be compared with modern day Tyrants. Macbeth had an elevated status for his heroism and dedication for the cause of Duncan as we come to read in Act 1,Sc 11.