I was wondering if anyone would mention dragons.
I was wondering if anyone would mention dragons.
I was wondering if anyone would mention dragons.
I was wondering if anyone would mention dragons.
Anyway, I'll throw in another vote for
kobolds and goblins.
Mongrelfolk also work well too. The PCs will almost universally underestimate them, making them nice surprise villains.
Also,
dopplegangers make the best roleplaying villains. These guys can cause serious trouble for the PCs (e.g., framing them for crimes, alienating family and friends, etc.) without ever even getting into combat.
And my favorite villain was an
assimar. Yes, that's right, an assimar. Whether you make an assimar villain evil or just misguided, the PCs will rarely expect to be betrayed by them. This race also works great if your players start showing a tendency to metagame ("oh, he's alright. He's an assimar!").