Villains (2001)

From the back of the book:

Tome of Ultimate Evil
Villains tie a world together with a unifying theme. Whether you're looking for a night's entertainment or an epic, campaign-sweeping evil, agents of darkness awaits you.

Right for your campaign
Each villain is written world-neutral, allowing easy placement into any campaign world. From fledgeling adventurers buying there first pieces of equipment to epic heroes wielding powerful magic, you'll fin challenging villains to oppose the forces of good.

New Powers
Villains have their own secret weapons! New spells, artifacts, monsters, and prestige classes lay in waiting.

User summary:

This book describes 21 different villainous NPCs, each described in two to five pages. In addition, there are eight new spells, fifteen magic items, four evil prestige classes and a new monster. It is meant for any D20 system fantasy campaign.