Queen Nehalennia serves as the primary antagonist in the Dream arc of the Sailor Moon manga and its film adaptation, *Pretty Guardian Sailor Moon Eternal*. Originating in the Silver Millennium, she existed as Queen Serenity's dark counterpart, styling herself ruler of the moon's shadowed core. Her first major act saw her crash Princess Serenity's birth celebration, confronting Queen Serenity. Queen Serenity ultimately imprisoned Nehalennia within a mirror dimension using the Moon Stick. During her sealing, Nehalennia retaliated by casting a potent curse ensuring the Moon Kingdom's destruction before the princess could inherit the throne, directly causing the fall of the Silver Millennium. Trapped within the mirror yet sustained by its power, Nehalennia endured beyond the kingdom's ruin. Millennia later, a solar eclipse weakened her prison, allowing her influence to breach the human world. Seizing this chance, she located Sailor Chibi Moon's future guardians, the Sailor Quartet, forcibly awakening them prematurely. Through dark manipulation, she corrupted them into her minions, the Amazoness Quartet, to spearhead her Dead Moon Circus. Her objectives centered on claiming the Silver Crystal, asserting herself as the Moon's true ruler, and conquering Earth. To achieve this, she first targeted Elysion—a sacred dimension within Earth—capturing its guardian, Helios, and corrupting the land with nightmare energy. This act forced Helios's spirit to flee into the dreamscape as Pegasus, seeking aid. Physically, Nehalennia possesses exceptionally long, wavy dark hair reaching the floor, typically styled with twin buns and ponytails. Her appearance features pointed ears, light blue eyes, and crimson lips. She wears ornate gold jewelry, including a choker with a red gem, and a headpiece featuring three crescent moons. Her attire consists of a dark dress with puffed sleeves, layered under a beige overskirt and a flowing lavender cloak adorned with a spiderweb pattern on the back. Her abilities encompass advanced dark magic, enabling curses that inflict widespread harm across dimensions. She manipulates dreams—particularly inducing nightmares—to exploit vulnerabilities. Her powers extend to energy projection, matter manipulation, and soul extraction. As an incarnation of Chaos, she corrupts beings, evidenced by her transformation of the Sailor Quartet. Her connection to the mirror allows interdimensional control, imprisonment of foes within glass shards, and self-sustenance through the dark realm linked to her existence. This realm, described as a parallel universe, grants her nigh-omnipresence within it and high-level regeneration. In the climax within Elysion, Nehalennia seized the Silver Crystal from Sailor Moon. However, the combined power of the Silver Crystal and the Golden Crystal—newly awakened within Tuxedo Mask—countered her assault. Empowered by the unified energies of all ten Sailor Guardians, Eternal Sailor Moon delivered the final blow. This caused Nehalennia to wither into an aged form resembling Zirconia before she and her mirror dissolved into dust, sealed permanently within the eclipse. While other adaptations depict alternate resolutions, the manga and Eternal films establish her dissolution as Chaos's manifestation. Her narrative concludes with the revelation that she, alongside other major antagonists, embodies a facet of the primordial entity Chaos.