Don't you want to snuggle it?

A Rat Beast is the layman's term for a magic creature that skulks about the Kellwood area at night. Considered weaker prey by the hunters, bounties on Rat Beasts are fairly low compared to that of vampires or other creatures. Rat Beasts are perhaps the most common monster however, and often make it as far into Kellwood as mid-town, whereas such creatures as vampires are typically found at the edges of the town and caught and killed fairly quickly. This is due in part to their relatively small size, the largest Rat Beast growing to roughly the size of a raccoon. Kellwood residents will usually dismiss these as ill opossums or raccoons should they see one.

They are omnivorous and will eat most anything, and will attack pets or people who threaten them viciously.

In appearance, the Rat Beast is a sickly and gruesome thing. Its greasy fur is rough and does not grow on certain areas, and it secrets an oily substance from these bald patches. The skin underneath is pink and mottled. The rat Beast has six "eyes", a main pair and two sets of rudimentary "false eyes". Like the rodent it takes its name from, Rat Beast's teeth are constantly growing, and a hole in the top of the snout accommodates the overgrown bottom teeth to give it a "horn". The Rat Beast uses this for defense and males use this horn to fight other males for mating rights or food. If the creature was not constantly using and wearing this horn down, it could potentially curl over its head and make opening its mouth fully impossible. The nasal passage is routed around the hole on both sides, giving the front of the snout a broader, arrowhead appearance.

Being a magical creature, the bite of a rat-beast is potentially dangerous. Should one scratch you with its "horn", the wound never heals. Pain may eventually fade, but the wound stays perpetually open. Permanent stitches are required to keep the wound shut.

Rayna, Ella and June typically are assigned to Rat-Beast control, a point of contention between Rayna and her boss Blaine, who thinks he is being chauvinistic and sexist by insisting they hunt these smaller monsters. Blaine insists it is important work and he does not intend to keep them assigned on "low bounty" because they are women, but because they are skilled at it. (He also is being protective of Ella and June who aren't as strong as Rayna, who can hold her own against a strong vampire.)

Victor went with Ella to slay these creatures shortly after losing sight in one eye to a werewolf attack, and received the Rat Beast scratch on the opposite side of his face because he didn't take the situation seriously.

The first appearance of a Rat-Beast in the webcomic was in Blaine's underground HQ, where he is keeping an assortment of creatures for various purposes. Tony, having possessed Blaine's body, used the creature to escape from the basement with Mye's wand.