Maloker is an extremely powerful villain from the Buffyverse, though he did not appear until the series departed from its original TV format and into the canonical comic books : he is a member of an ancient demon-race that once ruled Earth in the distant past and is the entity responsible for the creation of Earth's vampires.
Powers and Abilities
Maloker was a vastly powerful demon comparable to a deity, in fact he was shown as capable of overpowering demons, Slayers and deities with sheer physical force and was for all intents and purposes godlike in scale.
He could also reach any size and much like the First Evil was completely immortal, if slain in the physical universe his spirit would simply linger in an alternate reality and be capable of returning after some time.
However, due to being the creator of Earth's vampires he shared many of their weaknesses, such as holy items and staking, albeit his resistance was magnified due to his size, age and status - it was possible to "dust" him just like a vampire but required large items by which to do so (much as how it took an entire wooden beam to slay the ancient vampire, Kakistos)