A guy (narcissists are never female) who doesn't see things your way.

Someone too confident and full of themselves, walking like they own the world, they think they can do no wrong. Believes they are always right, and the best at everything.

Kendall hays

Somebody who says something overly positive about their accomplishments without any proof from other people.

It can also be somebody who shoves their accomplishments down your throat.

P

A person who gives 8,010,000,580 shits about themselves and -10, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000 about the person sitting next to them on the bus.

nar·cis·sist
/ˈnärsəsəst/
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noun
a person who has an excessive interest in or admiration of themselves.
"narcissists who think the world revolves around them"
A grandiose self image. A very inflated ego. A continuous need for attention. A big urge to be admired. And if that admiration is lacking or the narcissist is criticized, which is even worse, he lashes out recklessly.