By his appearance, he is an extremely old river spirit, evident by the countless wrinkles on his face, white-colored eyebrows and the thinning amounts of facial hair and lack of teeth, the Unnamed River Spirit is revealed to have a water-based body (similar to that of a dragon's) in his original form with multiple, wiry, and avian legs.
In his first introduction in the film, the Unnamed River Spirit is shown to be a disgusting, grimy, muck-infested spirit mistaken to be a "stink spirit" by many. However, Yubaba notes that he didn't seem like a stink spirit and ordered Chihiro to wash him. After being relieved of all the human-made trash that had clogged up his body, the Unnamed River Spirit was freed from all the gunk he was carrying and revealed himself to be a grand, dragon-like spirit.
Not much of the Unnamed River Spirit's personality is made apparent in the film. It is known that he is a very rich and powerful spirit with much influence in the Spirit World. He is shown to be very energetic once freed of his polluted burden and displays a hefty amount of gratitude to Chihiro, who freed him, by giving her a famous type of medicine as thanks. He is also generous, leaving a great amount of gold pieces on the ground as a tip to the Bathhouse workers for their service to him.
The Unnamed River Spirit is assumed to be the spirit of a very large and powerful river in the Human World. Due to humans consistently dumping trash and filth into his river, the Unnamed River Spirit was transformed into a filthy muddy creature that leaves a trail of sludge wherever he walks. In hopes to save himself from the pain of being grounded by human waste, the Unnamed River Spirit visits The Bathhouse where Chihiro helps him take a bath in the big tub. After pulling a bicycle (among countless other man-made artifacts) from his body, the Unnamed River Spirit shows gratitude by giving Chihiro a famous, emetic dumpling medicine and leaves the bathhouse happily in his original form, leaving a generous amount of gold as tips for the workers.
He is not seen again in the film.
- "Well done." - His only quote in the film.
- The Unnamed River Spirit is a character that alludes strongly to Spirited Away's theme of human corruption on their surrounding environments, as seen when Chihiro pulls a truckload of man-made waste and debris from his body.
- According to Yubaba, the Unnamed River Spirit is rich and powerful.
- The Unamed River Spirit is similar to Hedorah from the Godzilla series, as they both have a similar appearance and represent pollution.