Here are some suggestions to out-dark the Dark Lord!
Appearance: A creature with completely black skin and wearing tattered clothes, like a destroyed version of AQW's No Class. It's face however, is very pale, almost sickly. It is bald, has many fangs, and has pointed ears. It's hands end in long claws. In battle, it stands hunched over.
Story: When Nulgath came to power in OverSoul, the Darkness spread like wildfire. It infected all it touched, corrupting them into different forms. Some turned into fiends, others into forms simlar to that of Nulgath's loyal servant Revontheus. The worst however, were the ones that were completely overtaken by pure darkness and evil. They knew no allegiance besides that of their incessant thirst for human blood. While vampires had always been present on OverSoul, these Thirsters, as they came to be called, were a new sort of monster. Even now they still plague the lands, preying on any who come within sight.
Player: I thirst...
Enemy: Only your blood will quench my thirst.
1-hit: He runs and slashes one of his claws at you.
2-hit: He follows up the first slash with another from the other claw.
3-hit: He follows up the two slashes with a headbutt.
5-hit: He jumps and slashes at you three times, then bites you and kicks off, returning to the place he started.
Appearance: He is about the size of Vergil. He has pure black skin all across his body. He has no shirt, and you can see a six-pack. He does have a flowing tattered black robe that starts at his waist and covers his legs and feet. His head is a three-horned skull shaped like a bull's. He has black tentacles sprouting from his back and neck and has a black tongue hanging out of his mouth. His eye sockets are black and completely hollow. Also, in one hand he carries a jagged sword.
Story: Unlike his namesake, Thanatos is not a god of death. However, none of his opponents ever lived long enough to realize that. He was once a simple human mercenary, though more skilled than most. His jagged blade was the most famous instrument of death in OverSoul. Then, one night he was killed by an assassin from a rival merc company. Upon hearing of his death, a Necromancer that had been settling in the village decided to revive the famed killer for his own cause. Such a skilled fighter would make a useful minion. However,, the mercenary's will was much stronger than the wizard had intended, and he quickly gained free will. He slew his former master, who had only had that role for less than five seconds, and ran off to begin life anew as an Undead. He recovered his jagged blade and set off to challenge something difficult, as opposed to the easy kills he had found in life. He found out about the Great Fiend Nulgath, and decided to seek out him and his servants. After effortlessly carving a path through his guards, he found humself face to face with the Dark Lord. Instead of fighting the Undead Mercenary, he offered him a gift. Grand and dark powers in exchange for his eternal servitude. Thanatos accepted the offer without hesitation. But once againt the figghter's indomitable will was more than anyone could handle. Even Nulgath himself only kept Thanatos in his servace for a day. With more strength than ever, Thanatos set off to be a more powerful bringer of death than even his namesake, and so far all who've seen him would say he is. That is, if they were still alive to say so.
Player: There are worse things than death, so really I'm doing you a mercy.
Enemy: Do you think you can kill me? Been there, done that.
1-hit: He throws the sword at you.
2-hit: Hethrows the sword and follows up with a quick shot of dark energy.
3-hit: He flies over to you and swings his sword three times.
5-hit: His sword morphs into a long scythe, and he swings it down sending a large blast of dark energy at you.