A cat from The Binding of Issac. Guppy can be seen as items or have items referencing Guppy in the game such as Guppys collar, rotten head, paw, tail, etc. If the player can find three of these items involving Guppy in a single run, they will transform into Guppy, being able to fly and generate blue attack flies when damaging enemies. Guppy is depicted as a gray/grey and white or black and white furred cat with a dipstick tail and may have x marks around the eyes indicating that s/he is dead.