Celty Sturluson is a Dullahan, a supernatural being from Irish folklore who traditionally serves as a harbinger of death. Her history as such a figure extends back centuries, during which she rode through the countryside of Ireland. Her current situation began when she woke up one day to discover that her head had been stolen, taking with it most of her memories. This loss set her on a relentless journey to recover her missing head, a quest that eventually led her far from her homeland to the district of Ikebukuro in Tokyo, Japan.

Despite her fearsome mythical origins and her eerie appearance as a headless figure clad in black riding a black motorcycle, Celty possesses a personality that is strikingly normal, grounded, and approachable, especially when compared to the many eccentrics and criminals living in Ikebukuro. She is generally confident, optimistic, and kind-hearted, often going out of her way to help others she feels are in need. Having spent many years living among humans, she has developed a range of relatable interests, such as watching television and DVDs, playing video games, and surfing the internet, where she participates in online chats under the alias Setton. Nonetheless, she has her own set of irrational fears. She harbors a notable and comical phobia of extraterrestrials and has also developed a fear of traffic officers, who relentlessly pursue her for her spectacularly illegal driving.

Celty’s primary motivation throughout much of her time in Ikebukuro is the recovery of her stolen head, which she believes holds her lost memories and is potentially the key to her continued existence. She works as an underground courier, also known as a transporter, to support herself while she continues her search. Because she has no head, she cannot speak verbally. To communicate, she types messages on a PDA or cell phone and shows the screen to the person she is addressing. Her presence in the city, speeding through the streets on her black bike while wearing a helmet with cat-like ears, becomes a well-known urban legend, with many referring to her as the Black Rider or the Headless Rider.

Celty’s role in the story is that of a central figure around whom many of the supernatural and mundane conflicts of Ikebukuro revolve. While she tries to live a quiet life and just do her job, her unique nature and personal quest frequently draw her into the schemes of others. She is a member of the Dollars, a colorless online-based gang, and is one of the few people aware of its founder, Mikado Ryuugamine. She forms a deep, protective friendship with him, valuing him for accepting her true nature without fear. Her closest female friend is Anri Sonohara, another girl who harbors a supernatural secret, and the two frequently confide in each other. She maintains a professional but wary relationship with the information broker Izaya Orihara, who often hires her for jobs; she does not like or trust him, but their business arrangement persists. In contrast, she gets along very well with the incredibly strong but short-tempered Shizuo Heiwajima, who appreciates her quiet and straightforward demeanor.

The most important relationship in Celty’s life is with Shinra Kishitani, an underground doctor with whom she has lived for over twenty years. They first met when Shinra was a child and discovered her stowing away on a ship. Shinra has been in love with her since that time, and eventually, his feelings are reciprocated. Their relationship deepens throughout the series, with Celty openly declaring her love for him and the two becoming engaged. A major source of tension in their relationship is Celty’s head. While she is driven to find it at all costs, Shinra repeatedly tries to dissuade her, partly out of a selfish fear that she will leave him if she regains her memories. This culminates in the revelation that Shinra knew where her head was and kept it a secret from her, causing a serious rift that they eventually work to repair.

Over the course of the story, particularly by the events of Durarara!!×2 Ten, Celty undergoes significant personal development. She moves from being solely focused on her quest to recover her head to a greater acceptance of her life as it is. Living in Ikebukuro, she has found a home, a purpose, people who accept her, and a profound love with Shinra. She begins to question whether she truly needs her head to be happy, realizing that she might be willing to give up her past for the future she has built. This internal conflict, balancing her lingering need to recover her lost memories against her desire to stay with Shinra, becomes a central part of her character arc.

Celty possesses a variety of notable supernatural abilities. Her body is composed of a sentient, shadowy black substance that she can manipulate at will. She can shape this shadow into anything she imagines, from simple tools and protective armor to her preferred weapon, a massive, non-lethal scythe. This substance also masks her headless state, forms her black bodysuit, and can be used to enhance her senses, as she perceives the world through sensors in the shadows that emanate from her neck. She has superhuman strength, speed, and durability, and possesses an effective form of immortality, as her body can rapidly heal from most injuries. However, she is not indestructible, as she harbors a deep-seated fear that the destruction of her severed head could also kill her. Her primary mode of transportation is a black motorcycle, which is in reality her headless horse, a Cóiste-Bodhar, that she has named Shooter and can transform at will.