megalomaniac:
(plural: ‘megalomaniacs‘ — for the right pronunciation, please click here)
a person suffering from megalomania,
Tony is a megalomaniac; he thinks he’s the wealthiest and the best of all, and wastes the little money he has to prove it!
The people ruled by a megalomaniac, like Hitler, Idi Amin, Saddam Hussein, etc., know how hard it is to knock some sense into their leader’s stubborn head.
Most of our movie villains (antagonists) are portrayed as megalomaniacs who like to show their dominance on everyone around them but are finally defeated by the heroes (protagonists).
Almost all the religious scriptures contain stories of struggle between megalomaniacs (baddies) torturing the common man and altruists (goodies) trying to save the common man from the clutches of those megalomaniacs.

