Queen Nehelenia serves as the primary antagonist in the Dream arc of the Sailor Moon manga and its adaptation, the two-part film *Pretty Guardian Sailor Moon Eternal*. Her origins vary between continuities. In the manga and *Eternal* film, she emerges from the Silver Millennium era as the self-proclaimed queen of the moon's dark center, a dark mirror counterpart to Queen Serenity. She crashed Princess Serenity's birth celebration, leading to a confrontation where Queen Serenity sealed her inside a dark mirror using the Moon Stick. During this sealing, Nehelenia cursed the Moon Kingdom to fall and the princess to never inherit the throne. Within the original 1990s anime, Nehelenia ruled a peaceful kingdom on a distant asteroid. Her obsession with eternal youth ignited after an enchanted mirror revealed her future aged self. To preserve her beauty, she consumed her subjects' dreams, transforming them into Lemures monsters and forming the Dead Moon Circus. Her fear of aging eventually manifested as Zirconia, a separate entity embodying her revulsion toward old age and ugliness. During the Dead Moon Circus arc (adapted in *Eternal*), Nehelenia escaped her mirror prison through a solar eclipse. She brainwashed the future Sailor Quartet guardians into the Amazoness Quartet. Claiming sovereignty over the Moon Kingdom and Earth, she sought the Golden Crystal to solidify her power. Her invasion corrupted Elysion, trapping its guardian Helios and forcing his spirit into the form of Pegasus. She inflicted curses on Earth via nightmare attacks, exploiting the Sailor Guardians' insecurities and Mamoru Chiba's connection to the Golden Crystal. In *Eternal*, a flashback depicts Nehelenia's backstory with Queen Serenity and her curse on the Silver Millennium. After capturing Sailor Guardians and stealing the Silver Crystal, she faced defeat in Elysion. The combined power of the Golden Crystal (revealed within Mamoru) and the Silver Crystal, amplified by the Sailor Guardians' unity, overcame her. She withered into an aged form before disintegrating alongside her mirror prison. In the original anime's fourth season (*SuperS*), defeat by Sailor Moon and Sailor Chibi Moon similarly aged Nehelenia, forcing her retreat into the mirror. She returned in the fifth season (*Sailor Stars*), released by Sailor Galaxia to spread a nightmare-inducing mirror shard plague. After tormenting Sailor Moon and abducting Mamoru, Usagi's forgiveness granted Nehelenia her true wish: reincarnation as a child with a chance for a life free of bitterness. Nehelenia commands abilities including casting long-lasting curses, manipulating dreams and nightmares, creating minions like Lemures, and corrupting others such as the Sailor Quartet. Her magic frequently employs spiderweb and mirror motifs. Zirconia, explicitly identified in both anime and manga as a physical manifestation of her fears, acted as her proxy until their reintegration. Her design features long black or dark blue hair, pointed ears, a spiderweb-patterned cloak, and a crown with three crescent moons. When her mirror shatters or her power wanes, she transforms into a withered, elderly form.