Okay, I know this is gonna sound really weird, but the Grimm brothers included Sankt Niklaus (Santa Claus) in their analysis of global folklore, and guess who appeared alongside him when they studied the accounts from Austria?
Santa Claus has had many sidekicks in various parts of the world; the elves and reindeer, Black Pete, and Knecht Ruprecht. But none comes closer to Grimm-worthy feature than Krampus.
Who's Krampus? Krampus is an ugly imp with the long crooked horns of an antelope-- a rather demonic image. According to the legend, Skt. Niklaus made it a point to only visit the children on his "nice" list; he assigned Krampus the task of visiting all the naughty kids and scaring them into behaving.
While Black Pete and Knecht Ruprecht left coal for the naughty ones, Krampus had a different treatment for them. He'd terrorize naughty kids, sometimes kidnapping them, tying them to a branch upside-down and swinging them back and forth. Krampus carried a bundle of switches that he'd beat naughty children with.
I hope the producers of Grimm jump on this opportunity-- it's got so much potential! They've already labeled Santa Claus as a Gefrierengeber, and it'd be interesting to see an episode with Santa and Krampus arguing over their rounds for the year-- I'd be excited to see them mention why Krampus has only been visiting the kids in Austria lately.