Belieber legions. 'nuff said. They often invade facebook pages and do their stuff.
tribals, anti-semites, anti-gays, religious extremists and other bigots.
People who practice bullfight/hunting and get away with it.
People who use 'Autist' as an insult.
People who spread too much hate when it's undeserved. Tells a lot about their personality.
