Queen Nehellenia emerges from the moon's dark depths as the chaotic counterpart to Queen Serenity of the Silver Millennium, a dark reflection born from the same distant source as the queen of light. She embodies Chaos, the primordial force of destruction. Appearing uninvited through Queen Serenity's mirror during Princess Serenity's birth celebration, Nehellenia sought to impose balance between light and darkness. Rejecting any darkness, Queen Serenity sealed Nehellenia within a dark mirror using the Moon Stick. Before her imprisonment, Nehellenia retaliated with a curse: the Moon Kingdom would fall, and Princess Serenity would die before inheriting the throne. Millennia later, a solar eclipse weakened the seal. Nehellenia breached her prison and discovered the Sailor Quartet—Sailor Chibi Moon's future guardians—in cryogenic sleep within asteroids. She awakened them prematurely, brainwashing them into her minions, the Amazoness Quartet. Establishing herself as queen of the Dead Moon Circus from within her mirror dimension, she commanded followers like Zirconia. Nehellenia claimed to be the true Moon Queen and rightful heir to the Silver Crystal and Earth, aiming to conquer Earth by corrupting the sacred land of Elysion and seizing the Silver Crystal. Nehellenia invaded Elysion, hexing the land and capturing its guardian, Helios. She imprisoned him, cursing him into the form of a Pegasus. Commanding the Dead Moon Circus, she exploited a solar eclipse to descend upon Azabu-Juban, spreading darkness. Her circus tent drained energy from civilians to fully revive her. She tasked Zirconia and the Amazoness Quartet with locating the Golden Crystal and defeating the Sailor Guardians, while the Amazon Trio infected the Inner Senshi with Lemures to control them through nightmares. During the final confrontation in Elysion, Nehellenia deflected Super Sailor Moon's attack and trapped the Sailor Guardians and Tuxedo Mask in a kaleidoscopic dimension, forcing them to relive her fateful encounter with Queen Serenity. Nehellenia seized the Silver Crystal, intending to kill the Guardians and rule the universe. However, a kiss between Usagi and Mamoru broke Nightmare's hold, returning the Silver Crystal and enabling Sailor Moon's transformation into Eternal Sailor Moon. Channeling power from the other Eternal Sailor Guardians and Tuxedo Mask wielding the Golden Crystal, Eternal Sailor Moon speared Nehellenia and her mirror with Starlight Honeymoon Therapy Kiss. This destroyed Nehellenia, restored Earth and Elysion, and broke her curses. As her mirror disintegrated into sand, Nehellenia demanded Mamoru acknowledge her as the true Moon Queen before perishing. Her ultimate nature as an incarnation of Chaos was later revealed, aligning her with antagonists like Queen Metalia, Death Phantom, and Pharaoh 90, confirming her role as a manifestation of the primordial darkness opposing the Sailor Guardians.