Belldandy is the central figure of Oh My Goddess! and one of three goddess sisters who come to live on Earth. Her name is a transliteration of Verðandi, the Norse goddess of the present and one of the three Norns, which directly informs her role and character within the story's cosmology. She holds the high rank of First Class, Second Category, Unlimited license within the heavenly system, a status that reflects her significant power and responsibility.

Her arrival on Earth is accidental. Keiichi Morisato, a college student, mistakenly dials the Goddess Technical Helpline, and Belldandy appears to grant him a single wish. When he wishes for a goddess like her to stay by his side forever, the wish is binding, and she moves into his dormitory room, an event that soon leads them to find a new home together at a temple. This arrangement forms the core premise, as the stories explore their life together and the complications that arise from living with two other goddesses, her sisters Urd and Skuld.

Personality is Belldandy's most defining trait. She is depicted as exceptionally kind, patient, and warm, showing empathy to everyone without exception. Her kindness surpasses normal human standards, and she possesses a very strong, pure heart. This extends to a notable naivete, as she often fails to understand malicious intent or lustful implications, trusting others even when she should be cautious. While overwhelmingly gentle, she is not without complexity. She has a deeply possessive and jealous side, especially regarding Keiichi, which can manifest as powerful, uncontrolled bursts of energy or sudden storms. This protective instinct is so strong that she once stated she would save Keiichi over the world. Another unique quirk is her reaction to carbonated drinks; unlike alcohol, a small amount of soda makes her completely drunk, leading to uncharacteristically wild behavior.

Her primary motivation is her relationship with Keiichi. While she initially accepted her situation as a required duty, she eventually confesses that she had been watching over him from Heaven long before they met and genuinely loves him. Her role in the story is largely defined by this bond. She acts as the emotional anchor for the group, using her abilities to solve problems, help friends, and protect Keiichi from various supernatural and mundane threats. Her key relationships are with her sisters: Urd, the impulsive and meddlesome elder sister representing the past, and Skuld, the brilliant but jealous younger sister representing the future. These relationships create much of the series' dynamic, as the three very different goddesses learn to live together.

In terms of development, the character has shown a clear evolution. In the earliest manga chapters, Belldandy was depicted as more impulsive, careless, and prone to arguing with Urd, with Keiichi often caught in the middle. Over time, she matured into the serene and almost impossibly kind figure she is known as today. Her character design also evolved, shifting from an initially plain look with blue hair to her classic appearance with light golden-brown hair and a more mature, refined beauty.

Her abilities are vast, befitting her high rank. To prevent her power from causing unintended consequences on Earth, she wears a special earring on her left ear that constantly seals most of her magical strength. When unsealed, her power is nearly limitless; she once reconstructed an entire building from rubble, claiming the feat required only one ten-millionth of her true strength. Her known skills include levitation and flight, teleportation through mirrors, speaking with and understanding animals, communicating with machines, seeing emotions as visible auras, healing minor wounds, and being an exceptional cook. She is also considered the finest singer in Heaven. Her personal angel, a symbiotic being that amplifies her magical power, is named Holy Bell, and her elemental affinity is wind and air. Her energy on Earth is replenished through sleep rather than food, although she enjoys cooking and eating for pleasure.