Mard Geer was an Etherious of the Dark Guild Tartarus and is known as the "Underworld King" and the Definitive Demon. He is tall, lean, and has the appearance of a young man. Often seen wearing a smirk, Mard is a cool, collected, yet arrogant man who plays himself off as being extremely intelligent; he quite regularly refers to himself in the third person. Much like the rest of his kind, Mard belittles humans, and thinks of them as nothing more than insects.