You don't have to be around the magical community long before hearing such aphorisms as: "wiccans don't worship Satan" and "wiccans believe the devil is an invention of the Christian church." These people are unfortunately ignoring much of the history of the Horned God. During the inquisition and European witch hunts, the church equated a number of pagan horned gods and spirits to their villainous devil in order to convert pagans to Christianity. Among these were: Pan, Dionysus, the Celtic Cernunnos, Janicot, and Krampus. While the others are primarily spirits of creation and fertility, Krampus is to a greater extent a dark god associated with mischief and sorcery. In spite of how he has been portrayed, he guides and protects his followers, and was said to be a chief god in pagan witch cults and preside over full moon esbats. A papal bull during the inquisition decreed him to be the devil, and he is often alluded to in the Malleus Maleficarum or The Witches Hammer. Historically, December 5th or Krampusnacht was devoted to him, and people to this day speak of him prowling around and scaring kids on this night. Contemporary wiccans will likely refute any working with Krampus or relate to him by a secret name told only to initiates of their tradition. Outside of Wicca, Krampus is featured under various names in family tradition witchcraft as a watcher and protector against those who might do the family harm.
In parts of Germany, Austria, and the Alps region, he accompanies St. Nick on Christmas giving beatings to bad children with a stick or carries them away in a basket, never to be seen again. He is rumored to be a son of Hel, the Norse goddess of the underworld, and he stays there with her during much of the warmer part of the year. He is depicted as black hairy satyr-like creature that stands upright on 2 cloven feet and has a long pointed tongue that hangs out. Today, there are festivals throughout western Europe and the United States that celebrate Krampus as a cultural icon much like Santa Claus or the Easter Bunny.
As we see, claims that witches work with a dark horned god are not unfounded, but the origins of the Horned God Krampus are pagan, not Christian.