Death Knight (デスナイト) is a level 35 monster and was one of Momonga's favorite creatures to summon back in YGGDRASIL.
A Death Knight stands at 2 meters tall with a crooked body. It is equipped with both hands, a rippled sword called a Flamberge and a huge shield known as a Tower Shield. Death Knights are look upon as huge creatures equipped with an armor made of black metal with red bloodlines engraved on it.
Moreover, the armor has sharp thorns everywhere and looks like an incarnation of violence. Two demonic horns are protruded from the helmet, with the face being visible underneath. It has a disgusting, rotted face whose empty eye sockets are filled with hate and killing intent, glowing with a flashing red light.
Meanwhile in the Anime however, its left hand has a massive Tower Shield that covers three-fourths of its body. Whereas on its right hand, is a serrated sword. The sword is nearly one hundred and thirty centimeters long and coated with waves of terrifying red and black fog, agitating observers from nearby surrounding like a constant heartbeat.
Death Knights have two very important special skills. The first is the skill of drawing in the hate/aggression of those disturbed by the Death Knight's appearance to attack it. The second one can only be used once upon getting hit, but it allows the Death Knight to always survive one lethal attack as long as there is a certain amount of HP left. In other words, a Death Knight can survive anything fatal with 1 HP remaining no matter what kinds of attacks is thrown at it no more than one time.
Because of these two special skills, a Death Knight is often used as a meat shield by their Summoner to protect themselves from any harms way possible. Nevertheless, Death Knights are closely estimated to be level 35 monsters, due to having both the attack power of a level 25 and the defense power of a level 40. Ainz estimated that someone who could defeat the defense-oriented Death Knights by themselves would probably be over level 45.
Additionally, once a Death Knight managed to kill its intended target, that dead body would later end up turning into an undead thereafter. For those killed by a Death Knight, it is said their body reanimates as a Squire Zombie. What can be particularly frightening about the Death Knight's skill of turning the people it killed into Squire Zombies is that those same Squire Zombies could also make Zombies too from the target they killed. However, the zombies will revert back to being regular corpses if a Death Knight were to be destroyed first.
- In the Web Novel, the Death Knight almost won the duel that would have killed Gazef Stronoff if Ainz Ooal Gown did not step in. It also fights the Martial Lord in the Imperial Arena.
- If Death Knight is summoned normally, it will cease to exist after a short time but if it is summoned in combination with a corpse, the Death Knight seems to become a permanent existence.
- One Death Knight was captured by humans from the Baharuth Empire five years prior to the appearance of Nazarick.
- One of Ainz Ooal Gown's Death Knights is currently training to see if it could gain levels and learn martial arts. While it is still unknown whether or not the Death Knight can learn martial arts, Ainz noted however, that leveling up seems impossible for this undead.
- Originally in YGGDRASIL, the Death Knight should have stayed by its summoner’s side to await their orders and attack any enemies which approached. Yet due to the difference in the New World unlike in the game, it can actually leave its summoner to fulfill its orders, launching an attack of its own accord independently.
- A guild's mercenary system that summoned creatures in exchange for YGGDRASIL currency did not allow for the summoning of Death Knights.