Chao are fictional characters that appear in the Sonic the Hedgehog series of video games. They are small, childlike creatures that do not have a gender. They have a pudding-like body and act like human babies. They first appeared in Sonic Adventure.
In the Sonic games, Chao are digital pets. Several different types of Chao are in the game. The Chao can evolve into many different forms, depending on how the player raises it. The player can raise them and enter them into races or battles. They have also been a part of the games' story and are sometimes seen during parts of the games. For example, the character Cream the Rabbit has a Chao named Cheese, which she uses to defeat enemies.