Vampire

Vampires (ヴァンパイア) refers to a race of immortals with an affinity for blood and the night.

Types of Vampires
In Overlord, the author seems to set tiers for vampires:

True Vampire: Shalltear's race. Looks like a monstrous undead with very few human qualities. Among the most creepy-looking vampires of YGGDRASIL, true vampires are even uglier than the others. Resembles a lamprey.

Origin Vampire:

Lesser Vampire: Reanimated by other vampires' race traits. They are rather similar to zombies in that they possess minimum intellect.

Vampire Bride: The only kind of vampire that looks beautiful but deadly yet their combat abilities are low.

Vampiric Beasts: Animals with the characteristics of vampires. Shalltear summoned some of them by her skill.
 * Vampire Wolf
 * Elder Vampire Bat
 * Vampire Bat Swarm

Appearance
Most of the vampires in YGGDRASIL are far from the modern 'aristocratic, mysterious race' archetype of vampires. Instead, they look like a horrible mix of bat and human. Shalltear's beautiful appearance is just a result of customization by her creator.

Abilities
Vampires possess numerous special abilities, including powerful muscles and fast regeneration. As undead creatures, they are effectively immortal. Noted for their longevity and taste for blood, they are considered deadly heteromorphic monsters.

Basic Vampire Race Traits
Despite their staggering advantages over humans, vampires are not always invincible and can be slain through a number of means.
 * Fast Regeneration
 * Evileye of Temptation
 * Life Absorption
 * Create Lesser Race by Bloodsucking
 * Weapon Resistance
 * Ice-type Damage Resistance

Basic Vampire Race Weaknesses

 * Slow movement penalty during Sunlight
 * Vulnerability to Silver weapons (only lesser vampires)
 * Added damage by Positive Energy

Culture
Vampires prefer places where the sunlight does not reach. They have developed a rather twisted sense of superiority over the living. Hence they would not dwell within cities with prey aplenty, nor would they hide deep within the sewers, they prefer a luxurious underground abode. A situation where they would stay in a roughly built cave is non-existent.

Trivia

 * The official manga divides the main vampire hierarchy into three categories: Vampire, Origin Vampire and True Vampire.
 * In the Web Novel, a Vampire's basic difficulty rank is 60, which is equal to upper A-class (almost A+). However, it is said that A-class adventurers can be confident of victory, while B-class adventurers might be able to win with appropriate preparation.
 * Most Vampires could only create unintelligent Lesser Vampires, but the Vampires which Shalltear could make had nearly as much intelligence as a normal Human.