Buer is a spirit that appears in the 16th century grimoire Pseudomonarchia Daemonum and its derivatives, where he is described as a Great President of Hell, having fifty legions of demons under his command. He appears when the Sun is in Sagittarius. He teaches natural and moral philosophy, logic, and the virtues of all herbs and plants, and is also capable of healing all infirmities (especially of men) and bestows good familiars.
He has been described as being in the shape of Sagittarius, which is as a centaur with a bow and arrows. Additionally, and illustration of Buer, that has been later engraved, has been made depicting the demon as having the head of a lion and five goat legs surrounding his body to walk in every direction.