Megalomaniac (noun)

A person who has an obsessive desire for power, status, or wealth, often to the point of delusional thinking.

Origin:

From the greek μεγαλομανία (megalomania), from μέγας (megas) meaning "great" and μανία (mania) meaning "madness" or "frenzy".

Examples:

1. The dictator's megalomania led him to believe that he was above the law.
2. He was a megalomaniac who wanted to control everything.
3. The CEO's megalomania was causing tension within the company.
4. His megalomania led him to believe he could control the weather.
5. The megalomaniac's ambition knew no bounds.