Death

Death, also known as the Pale Horseman and The Angel of Death, was the oldest and most powerful member of the Four Horsemen of the Apocalypse and an ancient primordial entity of immense power. Having existed since the beginning of time alongside God, Death is so old he cannot remember who is older: himself or God.

Personality
Due to his nigh-omnipotent power and his incredibly advanced age, Death is completely detached from the rest of the universe, rarely showing himself connecting to the people or beings who live within it. He even went so far as to compare Tsubaki to a bacterium, as if to state that his view on the importance of demons is just like how demons view the importance of bacterium. The fact that he said this to Tsubaki is also notable considering how Tsubaki is the only person he has ever shown a level of interest in. He cares very little for major events of the world like The Apocalypse, and despite his coerced involvement by Lucifer, he only pays the events vague interest, resulting in his tendency to wander off from his assigned targets. Death also claims to be an acquaintance of God himself, claiming that the two both share a similar advanced age to one another and that neither of them can remember which is older anymore or even if they are the same age.

Despite being callous and uninterested at times, Death has a respect for the natural order of the universe. He explains to Tsubaki that there are times when it is difficult, but in the end, breaking the order in even the smallest way can cause untold chaos.

While he does not hate Tsubaki and Shiro, Death feels that the pair are an affront to the natural order due to their constant resurrections and seems to show a certain annoyance regarding their numerous resurrections. Even though he is capable of it, as a rule, Death himself does not normally resurrect people, though he can and might make exceptions or even "an exception once, not twice." He also seems to genuinely like, to a certain degree, Tsubaki as the two share an almost brother-sister bond; however, it is revealed that what he feels regarding her is much deeper than a familiar relationship. Unlike the other Horsemen, Death has a level of respect for humans, specifically the human soul. Death tells Tsubaki that the soul is stronger than anyone knows and that it can suffer much and be broken but can't be destroyed, not even by him.

Despite claiming to be totally indifferent to the Demons and Earth, Death has helped them on a number of occasions. He sharply criticizes Tsubaki for not following his earlier hint about souls and tells her bluntly that he'll help, but added, "Don't thank me. Clean up your mess." It is implied that he is not so much uncaring as he is above the petty struggles of the world, disliking being called on to fix things that he thinks should have been taken care of without bothering him. Death also has an appreciation for human food, especially junk food.

Background
The Darkness claimed not to know who Death was and that he doesn't know her. However, he had knowledge of the war between God, with his Archangels, and the Darkness. Due to the complicated nature of his age, it is unknown how and when Death came into being. Death does not remember how old he is and said that he could be as old, or even older than God. However, it is possible that God is older as The Darkness states she knows of God but not Death.

Death mentioned that he was there when God created the first beasts, the Leviathans, and even, as he said, "personally found them entertaining."

Death is the boss of all reapers. A large number of reapers gathered in the town where Lucifer was going to release Death in order to serve him.

Normally, Death is kept locked and chained in a magical coffin 600 feet under the Earth. The Host of Heaven only released him when God had something major planned such as the Great Flood.

Quotes

 * "He leash around my neck -- off. Lucifer has me bound to him. Some unseemly little spell. He has me where he wants, when he wants. That's why I couldn't go to you. I had to wait for you to catch up. He made me his weapon. Hurricanes, floods, raising the dead. I'm more powerful than you can process, and I'm enslaved to a bratty child having a tantrum."
 * "As old as God. Maybe older. Neither of us can remember anymore. Life, death, chicken, egg. Regardless -- at the end, I'll reap him too."
 * "This is one little planet in one tiny solar system in a galaxy that's barely out of its diapers. I'm old, Tsubaki. Very old. So I invite you to contemplate how insignificant I find you."
 * "Nothing lasts forever. Well, I do."
 * "I had a tingle I'd be reaping someone very, very soon."
 * "Try to bind me again, you'll die before you start. Nice Pickle Chips, by the way."
 * "I can't, just be friends anymore..."

Trivia

 * Death is the only Horseman confirmed to predate the Universe.
 * The Darkness stated that she did not know Death, which might bring into question Death's statement about him possibly being older than God.