Krypto is Superman's pet dog from the planet Krypton.Before Krypton exploded, Krypto was placed in an experimental rocket. Unfortunately, the rocket wasn't puppy-proof and a special gas put him to sleep. Years later, before arriving on Earth, he woke up fully-grown, and could even see in color because of Earth's yellow sun.He's taken in by a boy named Kevin and his family, and becomes the family pet. When there's trouble, he becomes Superdog.Superman eventually reunites with Krypto, but lets Kevin keep him because of his extremely busy schedule.