In demonology Seir is a Prince of Hell, who has 26 legions of demons under his command. He can go to any place on earth in a matter of seconds to accomplish the will of the conjurer, bring abundance, help in finding hidden treasures or in robbery, and is not a demon of evil but good nature, being mostly indifferent to evilness.

He is depicted as a man riding a winged horse, and is said to be beautiful.

Other spellings: Seere, Sear.

See also The Lesser Key of Solomon, Ars Goetia.