Monsters have been part of culture since the first humans huddled around their campfire, listening to spooky forest noises. The label originally signified a warning from the gods, an evil omen marked by deformity, yet another example of fear of the other. Altered humans have been labelled monsters, whether the changes were wrought by nature, or self-inflicted. Foot binding, neck rings, and lip plugs have all created monsters in the eyes of cultural outsiders, even when the transformations were desirable for participants.
Outsiders in this culture have 40 others ways to express their preferred inner monster (according to Wikipedia), though not all will be visible except to privileged viewers. Arguably, participants are still adopting monsterhood as a way to gain status in their own particular (sub)culture, and are still only monsters when viewed through another set of norms. From the subcultural perspective, it is the denizens of the mainstream that are the monsters (Gordon Gecko, take a bow).
Follow the logic, and we all have a bit of monster in us, though not everyone chooses to make it visible. The scariest are those that are most invisible — monsters that use the bland and normal to shield their truly grotesque nature. Jeffrey Dahmer springs to mind. So take a good look deep within, embrace that realisation that your own monsterhood is evidence of belonging to the species, and think about letting it out to play. On Halloween, of course.