An Agares is an intermediate demonic creature with a cunning intelligence. It looks like an eight-foot tall red goblin with razor-sharp teeth and black talons, wearing the clothes of a magistrate or high government official, but can also appear as an old man and will mostly be encountered in that form. They are usually called upon to serve as advisers or guardians, and in the latter case, they will choose deception over direct action in order to enforce their duties.

An agares will always have a nearby pet, either a basilisk, cockatrice, or a gorgon which it can direct telepathically. It can speak any language and has Darkvison with a range of 120 feet. It is immune to poison and earth magics (such as being turned to stone) and only takes half-damage against fire, lightning, and cold attacks. Magical weapons are required to hit an agares whose skin is as hard as stone.