Nyx is one of the main characters in the anime Neo Angelique Abyss and its sequel season, Neo Angelique Abyss -Second Age-. He is the founder of the Aube Hunters, a group that sought out Angelique because of her ability to purify. He presents himself as a very handsome young man who appears to be around 26 years old, stands 179 centimeters tall, and has long black hair that reaches a bit past his shoulders and blue eyes. His manner is that of an extremely mysterious and polite gentleman, and he habitually refers to Angelique as mademoiselle, the French word for miss, rather than by her name.

Nyx has lived for roughly two hundred years, and his long existence is tied to Erebos, the source of the Thanatos creatures that threaten the world. He functions as the core through which Erebos sends Thanatos into the world, which places him at the center of the conflict. His motivation is rooted in this connection: his only hope of freeing himself from Erebos lies in the Queen's Egg, so he traveled the world in search of a candidate and found Angelique. He wishes that, once she becomes the Queen, she will grant him a peaceful death, making his pursuit of her both strategic and deeply personal.

Despite his composed and courteous exterior, Nyx has an unusual vulnerability, as he is deathly afraid of the splashing sounds of water. In the story, his relationship with Angelique is the most significant one, as he both guides her toward her destiny and depends on her for his own release. His development revolves around this dependence and his desire for an end to his long servitude to Erebos. His notable abilities include his role as the conduit for Erebos's Thanatos, his extraordinary longevity, and his leadership of the Aube Hunters, all of which make him a powerful and enigmatic presence in the series.