Many flavors of troll:
Starts threads just to get a reaction (traditional troll): Kach-22i
Posts one liner vitriole in existing threads just to piss people off: creaturecat
Starts complicated discussions to show how smart he is: Shaun
Not sure that the neo-con evangelists here fit the "troll" classification, although their incessant and monolithic hammering away at the same topics should surely get some award.