According to Kryptonsite, Krypto, Superman’s super-powered dog from Krypton, may be appearing in episode 4.13 which would be titled "Krypto."

There is no word yet on how Krypto will appear in SMALLVILLE nor what the storyline will be. This news is still at the rumor stage but considering that the site reported rumors of Flash and Mxyzptlk, which both turned out to be right, one could predict that Krypto’s appearance could be a safe bet.