I made a pretty nasty undead bbeg in a 3.5 game by applying both the lich and vampire templates to a necromancer, then giving him levels of the Vampire Lord prestige class from Libris Mortis. He also had the Swarm Shifter template, with swarm of undead parts. His skull would hover in the middle of basically a whirlwind of bones. I let the skull make Vampire drain attacks too, but also it was vulnerable to PCs trying to target it directly.
The nastiest thing about him though was how many other undead he could control.
I made a pretty nasty undead bbeg in a 3.5 game by applying both the lich and vampire templates to a necromancer, then giving him levels of the Vampire Lord prestige class from Libris Mortis. He also had the Swarm Shifter template, with swarm of undead parts. His skull would hover in the middle of basically a whirlwind of bones. I let the skull make Vampire drain attacks too, but also it was vulnerable to PCs trying to target it directly.
The nastiest thing about him though was how many other undead he could control.