The Rat Fink is a green, depraved-looking mouse with bulging, bloodshot eyes, an oversized mouth with yellowed, narrow teeth, and a red T-shirt with yellow "R.F." on it.Other artists associated with Roth also drew the character, including Rat Fink Comix artist R.K. Sloane and Steve Fiorilla, who illustrated Roth's catalogs.
A Rat Fink revival in the late 1980s and the 1990s centered around the West Coast grunge/punk rock movements. The term fink was originally underworld slang for an informer, comparable to "stool pigeon", and ratfink is an intensified version of "fink." By the time Roth used this name for a character, the term had started to pass into more general usage.