Battlefield fans. Seriously, it isn't enough to let people know they like the games, they have to go and rain on the parade of anyone who happens to like a different shooter. We get it - you don't like CoD. We don't care.
Bungie, Bioware and Bethesda 'fans'. Anything either of these companies does with these games is heralded as the worst thing that has ever happened by their fans. If they change nothing, they are criticised for being stagnant and releasing a cheap cash-in. They change something minor and suddenly they've sold-out and hate their fans. Seriously, some of the 'fans' of these companies feel they are entitled to anything they want whenever they want it.
Some PC fans. Yes, I know that it is a minority of you and most PC gamers are charming eloquent people, like most console gamers. However, there is that small bunch that seems to think that because the spent more on their computer than a console costs they should be entitled to everything under the sun and any of those console-playing peasants that think otherwise are not worth listening to as they are not part of the glorious master race. Like I said, it is a small minority but that minority is very annoying.