In my experience the most diruptive players I've had the joy of playing along side were:
Now that I type that out... I'm noticing trends.
- A necromancy obsessed wizard, who wanted to kill everyone so he could raise them from the dead.
- A dragon obsessed pyromaniac sorcerer, who wanted to kill everyone by setting them on fire.
- A gold obsessed rogue, who wanted to kill everyone so he could loot their corpses.
I'm imagining all three in the same party.
1 and 3 would form an alliance, with 3 killing people to take their gold, 1 raising them to get soldiers, and both of them plotting to kill 2 who is burning up all the good corpses and gold with his fire.