The Krampus is sort of St. Nicholas' Mr. Hyde-like alter-ego. The two travel together, with St. Nick handing out the goodies and getting all the hugs, and the Krampus doing all the dirty work. This disturbing legend traces back at least 400 years, but it's likely much older. National Geographic explains more:
Krampus, whose name is derived from the German word krampen, meaning claw, is said to be the son of Hel in Norse mythology. The legendary beast also shares characteristics with other scary, demonic creatures in Greek mythology, including satyrs and fauns.
According to folklore, Krampus purportedly shows up in towns the night before December 6, known as Krampusnacht, or Krampus Night. December 6 also happens to be Nikolaustag, or St. Nicholas Day, when German children look outside their door to see if the shoe or boot they'd left out the night before contains either presents (a reward for good behavior) or a rod (bad behavior).
The head-shaking Catholic church and poo-pooing by fascists pushed Krampus underground for a while, NatGeo continues. But today the Krampus is back in the holiday spotlight. In Germany, Austria, Hungary, Slovenia and Croatia, teenage boys especially like to dress up as the Krampus in December, and some people enjoy exchanging Krampus-themed Christmas cards. Now, the Krampus is even gaining a following on this side of the pond, with Krampus art shows, Krampus beer crawls and Krampus rock shows all in the works this holiday season.
More from Smithsonian.com: