Nurarihyon is one of the principal recurring antagonists of the anime franchise GeGeGe no Kitarō, and he has appeared in most of its television series in some form. He is based on a traditional Japanese yōkai from folklore, a mysterious elderly figure who was said to slip into busy households in the evening and behave as though he owned the home, helping himself to tea and tobacco before leaving quietly. His name suggests slipperiness and elusiveness, and he is often associated with images of an old man with an elongated, gourd-shaped head. Within the Kitarō stories, he has gradually become known as the supreme commander of Japanese yōkai, though this reputation developed over time rather than being part of his earliest appearances.

In appearance, Nurarihyon is a humanoid yōkai resembling a thin, elderly man with a large bald head shaped somewhat like a gourd, a face marked by deep wrinkles, small sunken eyes, and stubble. He is usually dressed in elegant traditional clothing, such as a kimono with an outer robe or Buddhist-style garments, and some designs give him pointed ears or a walking cane. In his earliest manga and first anime appearance, however, he wore a Western business suit while posing as a wealthy human being, and his overall design has varied somewhat between adaptations.

His personality is consistently defined by cunning and manipulation. Nurarihyon is a schemer who prefers to work from the shadows, hiring, deceiving, or commanding other powerful yōkai to carry out his plans instead of confronting enemies directly. He is capable of cruel acts and is genuinely dangerous in some versions of the story, while in others he is portrayed in a more comical light, with clumsy schemes and an air of foolishness that undercuts his villainous ambition. His defining trait as a character is his reliance on others: he is a strategist and a planner rather than a straightforward fighter.

His central motivation across most adaptations is the destruction of Kitarō, whom he views as his greatest enemy and the main obstacle to his ambitions. He is persistent in this goal despite repeated failures, and in some versions he insists that no one else is permitted to defeat Kitarō, going so far as to intervene when another threat moves against his rival. His larger ambitions vary by series. In the original story, he disguised himself as a human, committed acts of terrorism, and tried to eliminate Kitarō to avoid being exposed. In later series, he plots to dominate the yōkai world and the human world alike, sometimes manipulating human leaders and other times rallying yōkai communities to his side.

His role in the narrative has grown considerably across the franchise. He first appeared in a single episode of the first anime series and was absent from the second. Beginning with the third series, he became a semi-regular enemy and rival of Kitarō, and it was in this era that his status as the supreme commander of Japanese yōkai was firmly established. Later series expanded his importance further, with the sixth series devoting its final storyline to a large-scale conflict orchestrated by him between yōkai and humanity. In some story arcs, when the yōkai community faces a threat greater than his rivalry with Kitarō, he temporarily cooperates with his usual enemies and commands yōkai forces, demonstrating that his leadership abilities are real even if his motives remain self-serving.

His key relationship is his obsessive enmity with Kitarō, which defines most of his appearances. He also interacts frequently with Kitarō's associates, particularly the yōkai Nezumi Otoko, who sometimes becomes an unwilling collaborator or victim of his schemes. Nurarihyon commands a circle of subordinate yōkai who carry out his orders, and in some adaptations he forms uneasy alliances with other major antagonists, such as the foreign yōkai leader Backbeard. These alliances are typically temporary and end in betrayal, as Nurarihyon ultimately serves only his own interests. He generally treats his followers as disposable, though occasional moments suggest a grudging attachment to those who remain loyal to him.

In terms of abilities, Nurarihyon was originally portrayed as a clever schemer with little direct combat power. As his reputation as the supreme commander of yōkai grew across the franchise, he gradually came to possess a wider range of supernatural abilities, though his true strength remains his capacity for manipulation and his authority over other yōkai. He can mobilize large numbers of spirits, command them in battle, and in some versions summon or direct specific yōkai forces. His deceptiveness allows him to infiltrate human society and turn both humans and yōkai to his purposes. In certain adaptations he proves extremely difficult to destroy permanently, either surviving defeats, returning through supernatural means, or even transforming into a monstrous form of immense power after absorbing negative energy or malice. In his earliest incarnation, he was ultimately defeated by being banished to the distant past, while other versions see him destroyed, revived, or left to plot again, cementing his place as one of the most enduring and persistent enemies in Kitarō's world.