These gentlemen/ladies differ from trolls in the sense that they are not anti-social, but they are an accepted and sometimes well-respected members who assume a sort of informal and unofficial leadership role. They use this position to intimidate and assert their views on newer and less established members and often push their weight around to mark territorial rights. They will generally try and behave properly, but subtly try and behave like moderators and preach about forum behaviour. They will also turn and insult people as they wish and surprisingly other forum members will turn a blind eye to them. They will usually "adopt" ownership of a single forum or a subforum of a board and hang out there frequently with their clan. (this feature is usually more common in larger forums)
These people are often the starting point of cliques because they can gather a group of yes-people around them in no time.
Beware of these people and watch out for them because they can be a lot more trouble in the long run than isolated trolls running loose.
Sometimes you just need an excellent troll to combat an established forum bully
Summed up wonderfully.
Some of you people should be ashamed of yourselves!
It's real and it's happening.