- You may be looking for Homestuck's underlings or Problem Sleuth' beasts, who are also called monsters.
The Half-Harley Manor monsters vary widely in appearance, with little to no shared anatomy between them; however the seemingly nonsensical parts making up their bodies are consistent in form from monster to monster. Each monster has a pitch black exterior with no eyes, but one or more mouths showing a bright green interior (not unlike the white and green of first guardians) with either rounded blunt teeth or sharp pointed fangs, and a varying number of mismatching limb-like appendages attached to their varyingly-shaped bodies or "heads", sometimes resembling the arms and legs of humans, other times tentacles or membraned wings such as those of a bat.
Though all of these limbs may be functional, with winged monsters capable of flight and monsters with legs capable of locomotion, the seemingly random placement of the limbs sometimes makes their functionality limited; a monster encountered in the trophy room has one pair of legs so much smaller than its other legs that they don't touch the ground, while another encountered in the foyer has arms large enough to function in place of its legs and walks on its fists much like a gorilla. The first monster to appear is described as a snake, but despite its long featureless body it moves not by slithering but by walking on a centipedesque multitude of humanoid legs and feet.
The Half-Harley Manor monsters act aggressively to all non-like animals around them, actively chasing Joey and Jude and attacking both of them given any opportunity. However they appear to lack any higher intelligence, being easily distracted through simple means; despite their lack of eyes, they are capable of detecting and paying attention to sources of light such as flares, and can be stunned by having bright lights such as a flashlight shone in their eyes; see abilitech.
The monsters seem at least partially motivated by food; pet food can be used to distract them, and one of the monsters attacking and eating Frohike suggests they have a taste for meat (though their varying dental profiles suggests diet may also vary from monster to monster). Joey incapacitating one monster by throwing mixed spices at it may suggest that they breathe like living animals, or that their tongues are sensitive to spices like humans' are.