Nyx

Nyx (ニュクス, Nyukusu) is a recurring figure revolving the Shin Megami Tensei series. A demon of the Night Race, Nyx is a high leveled demon, capable only to recruit or summon once players reached a sufficient high level. Nyx plays a much larger role in the Persona 3 universe, where she is known as the mother of Shadows and the harbinger of The Fall.

History
The goddess of the night from Greek mythology. Originally it was said that she was born from chaos, and her name means "the mother night." She is depicted as a goddess draped in long flowing black robes. Versions of her birth and origins vary, but one interpretation has her as a creator goddess, laying a silver egg that produces the gods responsible for the creation of the world. She gave birth to many offspring, including Light (Aether), Day (Hemera), Death (Thanatos) and the Moirae Sisters.

Appearances

 * Megami Ibunroku Persona: Boss
 * Persona 3: Death Arcana (Final Boss)
 * Persona 3: FES: Death Arcana (Final Boss in "The Journey")
 * Devil Summoner: Soul Hackers: Yama Clan
 * Shin Megami Tensei II: Yama Clan
 * Shin Megami Tensei: if...: Yama Clan
 * Shin Megami Tensei III: Nocturne: Night Race
 * Digital Devil Saga: Avatar Tuner 2: Nether Race

Megami Ibunroku Persona
Appearing under the name Asura Queen, Nyx, calling herself Queen of the Night, appears as the final boss for the Snow Queen Quest. Her ultimate goal is to create an "eternal night", and uses the Snow Queen Curse and the Snow Queen herself as a means of being brought back into the world. When the Demon's Mirror is used to free Ms. Saeko, the Snow Queen comes to her senses, causing the now-free Night Queen Persona to show herself. She is ultimately defeated. Appearing briefly with her are two unnamed, but recognizable, characters from the SEBEC branch of the game in masks; the Masked Girl indicates she created the world the characters are in, while the Masked Boy only wants a fight.

Shin Megami Tensei III: Nocturne
Nyx is an enemy in Shin Megami Tensei III: Nocturne, she belongs to the Night Race, and can be recruited or summoned once players reached Level 70 or above. She has strong affinities towards all magic and absorbs fire-elemental attacks. Another Nyx can also be seen in Ginza, where she owns a lounge. She appears to be a respected and helpful figure, where she advises the Hito-Shura to enter the Mantra via forging an alliance with Nihilo, and tells him the way of reaching there.

Persona 3
Nyx is explained as the personification of death itself in Persona 3. She is also the final boss in the story, although gameplay-wise the final boss is her avatar. In ancient times Nyx bestowed Death and Night to the world, where she is destined to bring the Fall. Nyx, however, lies in hibernation and can only be called by the appriser of the Fall, which happens to be the incarnation of the Arcana that was never meant to be - Death. When the Kirijo Group was experimenting on the Shadows, Mitsuru's grandfather, along with several scientists, knew about the Fall, and willingly embraced it. They eventually succeeded at amassing a large amount of Shadows within the experimental facility and rejuvenated Death. However, Yukari's father declined, and destroyed the facilities - causing Death to be forcibly split into thirteen separate Shadows. Defeating the individual parts would cause them to reunite to the 'main' thirteenth Shadow, which was sealed within the Protagonist. Death, while within the Protagonist's mind, assumed the amnesiac identity of Pharos. Therefore, it is not until the Protagonist defeats the remaining twelve Shadows, rejuvenating and reawakening the final Shadow, Death.

Assuming the form of Ryoji Mochizuki, Death was responsible for summoning Nyx, and became the harbinger of the Fall. After the protagonist manages to fend of the Avatar of Nyx, the Avatar shrugs the damage away, and proceeds to connect to Nyx's true physical body, the moon. As she descends to earth, S.E.E.S was rendered immobile, leaving only the Protagonist immune to her effect. Through the cheering of S.E.E.S and his friends' will to live, the protagonist ascended to the Moon and battled Nyx, where he used his own consciousness as the Great Seal, sealing Nyx away.


 * See also: Ryoji Mochizuki, Erebus

Persona 3 FES
Nyx was briefly mentioned in the playable epilogue of Persona 3: FES, namely the Answer. It is later revealed that Nyx herself is neither hostile nor malevolent, she was awakened from the sorrow, depression, and apathy of humankind, believing that humans were tired of living and thus, her duty to end their lives. Upon returning to the time where the protagonist seals Nyx, it is revealed that the protagonist is not planning to seal Nyx away from humanity, but Erebus, a manifestation of humanity's negative will and grief from contacting her to bring the Fall.