Polychrome is a fairy and the daughter of the Rainbow. She first appears in The Road to Oz, the fifth of the fourteen Oz books by L. Frank Baum. She also appears in later books in the series.
When Dorothy Gale, the Shaggy Man, and Button-Bright first meet Polychrome in the fifth chapter of The Road to Oz, she is dancing to keep warm, after accidentally sliding off her father's rainbow and landing on the surface of the Earth. (Her father withdrew his bow without realizing she'd been left behind.)
Polychrome is described as: "A little girl, radiant and beautiful, shapely as a fairy and exquisitely dressed.... She was clad in flowing, fluffy robes of soft material that reminded Dorothy of woven cobwebs, only it was colored in soft tintings of violet, rose, topaz, olive, azure, and white, mingled together most harmoniously in stripes which melted one into the other with soft blendings. Her hair was like spun gold and floated around her in a cloud, no strand being fastened or confined by either pin or ornament or ribbon."