Monster Girls are a special type of humanoid where the anthropomorphic character is a mix between a creature (both real and fictional) and a human. Which means some body parts/limbs of a creature has generally been added or switched on a human body. Most of them are an human torso on the top of a monster bottom body. One of the general rule is to keep the face and torso area human. The human is usually a female, though some rare male examples exist.

Fetishism involving around monster girls is referred to as teraphilia.

The trait should NOT be applied for:
* Species prevalent in various fantasy works, like elves, orcs, fairies and others.
* Entities and species prevalent in sci-fi works, like robots, androids or various aliens.
* Girl monsters who do not have visible external monster features
* Cosplayers dressing as monster girls.