Vampires are an incredibly rare type of undead.
They can't use any of the gods' magic, and even those with innate magic tend to be unable to use it. However, they have much greater physical strength and speed than a living mortal.
Appearance-wise, they are a paler, sallower-skinned skinned version of their mortal selves. The more well-fed they are, the less sallow their skin. They have slightly pointier ears, large fangs, and their eyes have no pupils. When they are not feeding, their eyes are yellow-gold. When they are enraged or feeding, their eyes turn red.
Vampires can heal injuries very quickly - quicker if they drink blood. And vampires must drink blood to continue surviving. If they stop drinking blood, they slowly go mad, then perish. When vampires "die", they turn into dust.
Nobody is totally sure how vampires came to be, but the general consensus is some kind of curse.
Vampires can only be turned vampire by other vampires. Though vampires feed on blood and can kill people by draining all their blood, this doesn't automatically cause someone to become a vampire. It seems there is some sort of esoteric ritual required. Luckily, this ritual doesn't seem to be common knowledge.
Sunlight burns vampires, and can "kill" them if they are directly exposed to it for very long.
Vampires can only enter a dwelling if they are invited in.
Vampires can't cross running water. Nobody is really sure how that works.
Vampires are repelled by holy symbols of the God of Death, and can be badly injured by holy water in particular.
Most animals are repulsed by vampires
Vampires can only survive from the blood of people similar to themselves. For example, a human vampire can only drink blood from somebody who is of direct human descent.
Vampires aren't repelled by garlic itself, but are repelled by garlic flowers.
"Killing" a vampire without just putting 'em out in the sun is a rather protracted affair - they must be staked through the heart, beheaded, and have their mouth stuffed with garlic