I posted a campaign summary of the first session of my Cormyr campaign a week ago or so. If you read that post, you are probably already somewhat familiar with Lasander Highmoon, the NPC that hired the party to retrieve his supposed "stolen merchant wares" from the Rogues of Tilverton. Highmoon introduced himself to the party as a merchant from Arabel and proprietor of the Red Sun Trading Coster.
Some simple investigating from the party would have revealed much about Highmoon, had they not been so impulsive (or greedy.) For one, Highmoon seemed to know a lot about Tilverton, and more importantly the thieves guild therein. He knew a lot about the intricate sewer network the rogues use to smuggle goods, the black market in the sewers, and he even knew where his goods were being kept and the main access points to get into the place. In other words, he knew a hell of a lot more about this city than any simple merchant from another city should know.
The PC's never bothered to talk to any other locals about Highmoon. They never asked any questions of the man. Some of the locals likely would have pointed out that Highmoon is, in fact, a local of Tilverton. They also never checked into this supposed merchant company he owns. A quick public record search would have revealed there is no merchant company called "Red Sun Trading Coster" in Cormyr.
The PC's were rather curious at the large sum of money they were to receive for retrieving the goods (1,000 gp), but their lust for money overcame their sense of curiosity, and thus they attempted to raid the warehouse that very night, which was a botched effort entirely.
So, who is Lasander Highmoon really? He is a pawn himself, but a smart one. He serves a death cult devoted to the dead god Myrkul, who operates out of the sealed off crypts underneath the city of Tilverton. What exactly is in those crates that were stolen? A piece of an ancient evil artifact called the Crown of Horns, which contains the essence of Myrkul within. I'll go into more detail about this item in a later post.
Highmoon is a zero level NPC, and one whom will likely be a focus of the party's attention when they finally figure out what he's up to (if they do find out anyway.)
As I know they'll meta-game the hell out of this guy once they figure some things out, I imagine they'll likely be terrified to confront him for fear that he is some evil high level cleric capable of obliterating them at lower levels. He, of course, could do no such thing, and were the party to search him out and manage to confront him, they'd slay him rather easily, but they won't do that...not for a while at least because they will dwell in terror of this NPC.
A zero level NPC, with the proper backing and means, can become a true horror in the eyes of your players, and especially when they don't know that he's just a common man. Villains in the campaign are supposed to be crafty and cunning, and they don't have to be of a high level to terrorize your party. With the proper motivation and means, even a common man can be a threat to a group of adventurers.