Megalomaniac - ???

I love learning new words.  I'd never heard this one so I looked it up:

What is a megalomaniac person?

A megalomaniac is a pathological egotist, that is, someone with a psychological disorder with symptoms like delusions of grandeur and an obsession with power. We also use the word megalomaniac more informally for people who behave as if they're convinced of their absolute power and greatness.

I've never known a person that fit that description.  Now, I think I do.  Hopefully that will be a trivia question on a future cruise!