Back in the early 90's I was involved in a high level AD&D game. During one session, our band of adventurers witnessed a huge army of the Undead marching towards the city we had vowed to protect. As we dicussed what sort of action to take against the undead, we noticed a lone figure riding a nightmare at the back of the army, who appeared to be a skeleton in heavy armor. Immeditately the party freaked out and declared the mysterious being to be a death knight. I immediately squashed that idea.
"What!?! It couldn't possibly be a death knight! There are only, like what, 10 in existance, or something like that. What the hell would one of them be doing here?"
The party continued to doubt my ranger's line of thinking. So, I continued.
"Look, if he was a death knight, why is he way back here, far behind the main army? Why isn't up front, leading the undead into the city? I'm telling you, it can't be a death knight!"
Well, that convinced them. On our first round of attack against the mysterious being, it let lose a 20d6 fireball, the trademark attack of a death knight. The party's barbarian failed his saving throw, and nearly all his magic items missed their saving throws too and were destroyed. The rest of the party was nearly dead from the firery blast.
My character's only response to the hatred in the eyes of my fellow party members was, "Well, what the hell do I know about the Undead? I'm just a ranger, after all!"