A sore loser is someone that can't accept their loss

Specifically a football match

Someone who sucks too much to win, but still hates losing.

Vassily, meaning loser of the sore in Gaelic. The sore meaning a cold sore on the mouth and loser meaning one that loses. Together it creates Vassily.

Tuila'epa Sa'ilele Malielegaoi
Samoa's Ex Prime Minister.

a person who can not accept loss at all. Will try to make any excuse as to why they should’ve won/why their opponent should’ve lost. These people are extremely stubborn.

Someone who behaves like a petulant child when they lose. They accuse the other side of cheating and blame everyone but themselves for the loss.