Demon

A Demon is a hostile spirit from the Nevernever other than a faerie.

Description
Most of the beings the spirit world usually don't care much about mortal business. Those who do, generally out of hunger or a need of terrifying them, are called demons.

Harry Dresden states that they know when you've been bad or good, and they make Santa Claus look like an amateur. Demons don't have a soul, don't worry about good and evil or right and wrong, and if they're inclined to eat someone, they will. There are, however, rules of protocol that demons are obliged to follow, such as offering resistance to any mortal who called them and trying to end the life of the wizard that called them.

Storm Front
In Storm Front, a Toad Demon invades Harry Dresden's apartment. It follows Harry and Susan Rodriguez down to the Dresden's lab where Harry encloses he and Susan inside of his bronze summoning circle. Harry and Susan transport outside with the aid of a potion—the demon follows. The Shadowman shows up claiming the demon is his.

Fool Moon
In Fool Moon, Harry calls up Chaunzaggoroth to get information on Harley MacFinn.

Grave Peril
In Grave Peril, using a ritual spell in his lab's copper Circle, Harry attempts to summon Azorthragal, Harry ends up summoning the Nightmare instead assuming Azorthragal is the Nightmare. Harry binds the Nightmare to him so he can't hurt anyone else forcing it to come after Harry only.

Blood Rites
In Blood Rites, Harry fights monkey-like guardian demons that looked like a "demented purple chimpanzees" and threw fiery goop to rescue a box full of Temple Dog pups for Brother Wang. Harry dubs one of the demons "Kongtron" because it was about eight feet tall and was formed when the smaller demons came together in a fashion similar to the children's cartoon giant robot Voltron. Harry explained to Thomas Raith that is was a Shen—a chinese spirit creature. Ebenezar McCoy makes reference to the scion of demons when talking about Jared Kincaid.

Dead Beat
In Dead Beat, Captain Anastasia Luccio tells Harry that the Red Court vampires pursed the White Council into Faerie and called up both demons and Outsiders from the Netherworld.