Kalshazzak

Kalshazzak is the toad demon summoned by Victor Sells. It appears in Storm Front.

Storm Front
The demon arrives at Harry Dresden's apartment while Dresden is preparing for his date with Susan Rodriguez. Dresden is in the shower and Rodriguez in the living room when the demon breaks through the door and pushes past the threshold. It then spits acid at Dresden destroying his furniture.

Harry takes Susan retreat to his basement lab and enclose themselves in the summoning circle there. The demon pursues them, and they escape with the help of a previously brewed escape potion. The demon tracks them down in the street where the potion dropped them. Harry destroys the demon's physical body by using the power of the storm.

Victor Sells again summons Kalshazzak at the lake house, but allows Dresden to learn the demon's name. Harry frees the demon from Victor's control, allowing it to turn on the warlock.