Kirby is a small, pink, spherical creature (occasionally described as a living pink marshmallow) with large red feet, stubby arms, and trademark pink cheek-blushes. His body is soft and flexible, allowing him to be flattened. His first appearance took place in the 1992 video game Kirby's Dream Land, where he was portrayed by a 2D sprite; since Kirby 64: The Crystal Shards for the Nintendo 64, he has made several appearances in 3D. He has been featured in other video games from Nintendo, on Nintendo's merchandising, on comic books, and even on a television show. Kirby also appears in the Super Smash Bros series.

Kirby hails from the planet Pop Star, where he lives in a dome-shaped house in the kingdom of Dream Land. His appearance has changed subtly over the years, becoming more rounded and defined, mainly in his face and larger eyes.