Queen Nehellenia rules her own kingdom, presented as a dark counterpart to Queen Serenity of the Silver Millennium. During Princess Serenity's birth celebration in the manga continuity, she arrived uninvited, cursed the infant princess to never inherit the throne, and prophesied the Moon Kingdom's fall. Queen Serenity subsequently sealed Nehellenia inside a dark mirror world using the Moon Stick, an imprisonment that allowed her to survive the Silver Millennium's destruction. In the 1990s anime, Nehellenia (then Queen Helenia) governed a peaceful realm. Obsession with eternal youth consumed her after a magic mirror revealed her future aged self. To preserve her beauty, she devoured her subjects' dream mirrors, transforming them into Lemures and founding the Dead Moon Circus. Envious of the Moon Kingdom's prosperity, she sought the Golden Crystal but was sealed within a mirror by Queen Serenity after Helios rejected her. Millennia later, a solar eclipse weakened the seal, enabling her return. Nehellenia breached her confinement and established the Dead Moon Circus to spread darkness and nightmares across Earth. Discovering Sailor Chibi Moon's future guardians, the Sailor Quartet, she prematurely awakened and brainwashed them into becoming the Amazoness Quartet, her primary minions. Nehellenia declared herself the true Queen of the Moon and rightful heir to the Silver Crystal, aiming to conquer Earth and the Moon Kingdom. Her strategy involved capturing Helios, priest of Elysion, and corrupting that realm to locate the Golden Crystal for ultimate dominance. In *Sailor Moon Eternal* (adapting the manga's Dream arc), Nehellenia directed the Dead Moon Circus through Zirconia while mostly concealed within her mirror. She orchestrated an invasion during a solar eclipse, creating a dark barrier around Tokyo and dispatching the Amazoness Quartet to drain human dream energy. Her curses afflicted Mamoru Chiba (Tuxedo Mask) and later Usagi Tsukino (Sailor Moon), causing physical deterioration linked to Elysion's corruption. After Zirconia captured Sailor Chibi Moon, Nehellenia forced Helios to reveal himself, seized the Golden Crystal, and escaped her mirror prison. The climactic confrontation occurred in Elysion, where she faced the Sailor Guardians and attempted to claim the Silver Crystal. A flashback reiterated her past curse upon the Silver Millennium at Princess Serenity's birth celebration. Eternal Sailor Moon, empowered by all Sailor Guardians and the Golden Crystal, ultimately destroyed her mirror form, causing Nehellenia to shrivel into an aged crone before vanishing. Her powers encompass potent black magic, dream manipulation, and debilitating curses. She corrupts environments like Elysion and individuals such as the Sailor Quartet. Nehellenia extracts and consumes dream mirrors to sustain youth and power, creating Lemures from corrupted dreams. Her mystical mirror connection allows dimensional perception, influence projection, and victim entrapment. Her manga and *Eternal* defeat reveals her as an incarnation of Chaos, linking her to primordial antagonists like Queen Metalia and Pharaoh 90. After her sealing, Chaos consumes her in the Stars arc. Conversely, the 1990s anime concludes differently during Sailor Stars: Released by Sailor Galaxia, Nehellenia shattered her own Dream Mirror, infecting humans with its shards and kidnapping Mamoru. After subjecting the Sailor Guardians to nightmares, Sailor Moon's forgiveness granted her a second chance; she was reborn as a child in her original kingdom, free of malice. Visually, she possesses long, flowing dark hair, pointed ears, and ice-blue eyes. Her attire features a crown or head jewel with crescent moons, a golden choker bearing a red gem, and a cloak adorned with a spiderweb pattern. Defeat causes her youthful form to deteriorate into a wizened, aged appearance.