The river spirit in “Spirited Away” is Haku. He is the human-looking boy who guides Chihiro through the spirit world and later appears in the form of a white-and-green dragon.
Haku's full spirit identity is the Kohaku River spirit, also known as Nigihayami Kohakunushi. Chihiro remembers this when she recalls falling into the river as a child; Haku carried her safely to shore. That memory restores his forgotten name and breaks Yubaba's control over him.
The film also contains another important river-spirit scene, which causes a common mix-up. Chihiro's first major customer at the bathhouse is a polluted river spirit, but that character is not Haku and is not given the same personal identity. Haku represents a river whose course was destroyed by human development, tying his story to themes of environmental loss and memory.
Haku is voiced by Miyu Irino in Japanese and Jason Marsden in the original English dub. His bond with Chihiro is central to the film's emotional arc.