This article is about Krypto Mouse. The term Krypto can also refer to Krypto the Superdog.
Krypto Mouse is secretly Fuzzy, little Tommy Ewell's pet mouse, who grows large as a result of an experiment by Professor Egglehead and gains super powers but keeps his mouse personality. Krypto Mouse patrols Smallville for a time, causing some to confuse him at a distance with Superboy. Eventually, Krypto Mouse's abilities fade away and he returns to normal (SB No. 65/3, Jul 1958: "The Amazing Adventures of Krypto Mouse").