Hellish Minions

Familiars: Lesser spirits and entities that aid witches, wizards, sorcerers, and the like. They can either be summoned or heck even created due to the familiar being connected with the summoner/creator, they would take any form though it's normally the form of an animal or human but there would be something very off or abnormal about them such as having a sinister aura around them or look distorted or deformed. Particular familiars such as Parway and Ugly Bird appear in the works of Manly Wade Wellman.

Irvund: A breed of hellhound that would act as a familiar to the summoner to be used as personal security, they resemble mundane dogs such as dobermans but its normally dark colored with a foul disposition. Demon cults would summon these things and use them as guard dogs; having them for security purposes in case of trespassers 

Xic: Small minor demons used to inflict pain on the summoner's enemies, they take the form of two legged, skull-headed mosquito demons. Though these things are stupid, they are very loyal to who ever summons them.

Imp: A lessor type of demon and most often summoned by summoners, demon lords, and half-demons. Their forms can vary but the most common form would be that of a small humanoid being with a skeletal visage, bat wings, horns, spiked tail, claws and fangs. These guys are very useful and loyal to whoever summons them and much more prized than other familiars.

Parway and Ugly Bird (c) Manly Wade Wellman
Irvund and Xic (c) Dark Matter