The Why-wolves are characters that appear in the episode "Donny." They are monsters that resemble werewolves, but have a more inquisitive nature, and will sometimes pause to give lectures. One Why-wolf explains that their species is possessed by the spirit of inquiry and blood-lust.
According to a Why-wolf in the episode "Donny," the Why-wolves are usually kept in check by Obnoxygen, a gas produced by Donny the ogre that is deadly to Why-wolves. However, if left unchecked, the Why-wolves would eat the House People and grow in population until they attract the Cosmic Owl, who will subsequently devour them.
They resemble classic, modern werewolves, although by simply tearing away tufts of fur, they transform into more civilized versions of themselves, in which they wear gray suit tops and glasses. One was seen smoking a pipe. Some Why-wolves have two heads with one eye on each.
- According to a post on the Frederator Blog, Marceline's dress in "Henchman" is made from Why-wolf skin. Ironically, Marceline turned into a wolf to scare Jake.
- Their species name is a pun on "Werewolf."
- The Cosmic Owl is most likely their natural predator.
- The lecturing Why-wolf's tone and cadence are reminiscent of those of the narrators of a series of science education films produced by Bell Labs in the 1950s and 1960s that were often shown in schools and on educational television through the 1970s.