Esmeraude, also known as Esmeroldo in some adaptations, is a major antagonist appearing in the Sailor Moon R anime series. She is a high-ranking member of the Black Moon Clan, an organization from the 30th century, and serves directly under Prince Demande, the group's leader.

Her background establishes her as a vain, selfish, and deeply jealous individual. Esmeraude’s primary motivation is her obsessive, unrequited love for Prince Demande. She desperately wishes to become his queen and is fiercely possessive of him. This infatuation fuels her intense hatred for Sailor Moon, whom Prince Demande becomes interested in, viewing the heroine as a rival for his affections. Her role in the story’s narrative is to act as a primary field commander for the Black Moon Clan after the failure of her comrade, Rubeus. She takes over the mission to conquer present-day Tokyo, find the future Chibiusa, and eliminate the Sailor Guardians. She exhibits a cunning and deceitful personality, manipulating situations to her advantage and showing little loyalty to her allies, as she cruelly taunts Rubeus for his failures and leaves him to die aboard his exploding spaceship.

Esmeraude has several key relationships that define her actions. Her fixation on Prince Demande is the central pillar of her character, leading her to secretly attack him from the shadows to prevent him from being distracted by Sailor Moon. She holds a one-sided rivalry with Sailor Moon, driven entirely by jealousy. While she is generally pompous and dismissive, she displays a certain vitriolic camaraderie with Saphir, Prince Demande’s younger brother, who provides her with the Dark Wedges she uses in her plans. Despite knowing that the mysterious entity Wiseman is untrustworthy, her desperation to gain power and Demande’s affection drives her to seek his aid.

This decision leads to her dramatic and tragic development. In her desperation to destroy the Sailor Guardians and win Prince Demande’s love, Esmeraude goes to Wiseman, who grants her a cursed crown infused with the power of the dark crystal. The crown is intended to give her immense power, but the dark energy is too great for her to control. As a result, she undergoes a monstrous transformation, losing her humanoid form and becoming a rampaging, mindless dragon. This beast is described as the physical manifestation of her own subconscious hatred and obsession. In this bestial state, she attacks the Crystal Palace and battles the Sailor Guardians.

Regarding her notable abilities, in her human form, Esmeraude wields a large, sharp-edged fan as her primary weapon, suggesting skill in the martial art of tessenjutsu. She also has the power to create and deploy Dark Wedges—spires that inject dark energy into the Earth—and commands a variety of monster minions called Droids. After her transformation, she gains immense physical power as a dragon, including scaly skin, sharp claws, the ability to breathe fire, and incredible durability that allows her to withstand combined attacks from multiple Sailor Guardians. Despite this newfound strength, the transformation robs her of her intellect and sanity. She is ultimately destroyed by Sailor Moon’s Moon Princess Halation attack, which reverts her to her human form before she falls into a dark void. Even after her death, her signature, maniacal laughter continues to be a lingering nuisance to Wiseman, who admits that it always gives him a headache.