Coo is an owl with purple feathers (gray in Kirby's Dream Land 3) that cover most of his body. He has a yellow beak and a white belly with purple feathers that form three stripes on it. He has two wings with black tips and white undersides, as well as purple tail feathers. His eyes are surrounded by black feathers that form three triangular markings that somewhat resemble eyelashes, and he has yellow talons. His feathers form several spikes on his head, though the exact number varies between games.

(Source: Kirby Wiki)