Kakistos

Kakistos or kissing toast as Buffy misheard arrived in Sunnydale looking for 'the slayer.' The slayer that he was after however was Faith. It's well documented in the Buffyverse that vampires who survive for centuries gradually take on demon attributes. Kakistos was so old that he had a Greek name! His hands and feet were cloven but what amused me was that as well as these goat-like appendages he had a little goatee beard as well.
As vampires go he was very powerful (which obviously goes with his age) and he led a clan of vampires in Missouri until he came into conflict with Faith. Kakistos killed Faith's watcher in such a way that deeply shocked Faith and affected her to the extent that she fled Missouri but not before scarring the vampire's face with an axe.
Interestingly Kakistos, perhaps the oldest vampire we've seen arrived in town with Mr. Trick an extremely modern computer literate vampire.
Due to Kakistos strength and size it took both Faith and Buffy to defeat him.

His name is ancient Greek meaning "The worst of the worst." He was first seen in Sunnydale tracking down Faith, who had scarred him across the eye. He, like the master practised ancient rituals and thought in a very traditional vampire way.

He was killed when Faith thrust a giant piece of wood through his chest