The worst isn’t the screams or the snow or the mind-numbing blare of “Night on Bald Mountain“ on repeat. It’s the cowbells: a rusty jangle that means the Christmas monsters are coming.

Until Jan. 6, demons, witches and monsters haunt Europe.

The season of terror actually begins on Dec. 5, the eve of Saint Nicholas’ Day, with public parades of the saint’s supposed companions: Across the Italian, Austrian and Slovenian Alps, cowbell-slung demons called Krampus storm mountain towns. In France, the legendary serial killer and butcher Pere Fouettard (Father Whipper) threatens naughty children with his whip, while in Belgium and the Netherlands, a controversial child-kidnapper called Zwarte Piet (Black Piet) rides through canals on a steamship.

Like relatives returning home for the holidays, more monsters show up with increasing frequency as Christmas approaches. Every night from Dec. 12 until Christmas Day, the trollish Yule Lads peep through windows, snatch sausages and gorge themselves on stolen skyr in Iceland. On Dec. 25, goat-footed Kallikantzaros goblins emerge from underground and demand piggyback rides in Greece, Bulgaria, Turkey and the Balkans, and Germany’s Frau Perchta creeps into homes to slit open bad children and stuff their bellies with straw. Both do their mischief throughout the Twelve Days of Christmas until Jan. 6, when Italian children finally hang their stockings and the witch La Befana shows up with lumps of coal. And with legends and names that vary from region to region and even village to village, these are only a few of the continent’s mythical troublemakers played annually by adults in costume.

Here is Dec. 5 Krampus procession in Tarvisio, Italy, an alpine town close to the Italian borders with both Austria and Slovenia:

Photo by AJ Stephen A Dec. 5 Krampus procession.

Photo by AJ Stephen The Krampus carry broken branches as whips for naughty children (and adults).

Photo by AJ Stephen Traditional oversized Krampus masks and fur suits are hand-made.

Photo by AJ Stephen After accompanying St. Nicola into town, the Krampus terrorize onlookers with whipping and maulings.

Photo by AJ Stephen Only the members of a secretive Krampus fraternity may play a Krampus on Dec. 5.

Masked mayhem has always marked celebrations around the winter solstice (the night of Dec. 21, this year). In Roman times, December brought Saturnalia, a festival that reversed the social order: masters served dinner to their slaves, the rich gave gifts to the poor and to each other, and everyone went out in disguise—including slaves disguised as free men—to gamble and drink.

Even before the Romans, points out historian Stephen Nissenbaum, author of the Pulitzer Prize-nominated book, The Battle for Christmas, December was a disorderly time: “By some time at the end of November, the harvest and post-harvest work was done. What followed, if you were a man, was a period of leisure. Furthermore, the beaujolais nouveau was in, as it were… People were getting drunk.”

Back when Christmas was more about drinking, America had monsters too.

In the 1600s, early Bostonians celebrated Christmas disguised as animals, as members of the opposite sex or with face paint, in order get drunk and disorderly without being recognized, explains Nissenbaum. Caroling at the time meant dancing. Wassailing meant going door to door demanding food, alcohol and money.

The annual debauchery got so bad–think public orgies—that from 1659 to 1681, Massachusetts’ Puritans banned Christmas altogether. But the monsters never left; later, around Christmastime in 19th century Appalachia and Pennsylvania Dutch Country, wealthy families would be mobbed by requests for drinks and their children frightened into niceness (as a service) by masked marauders and cross-dressers called Belsnickels.

Of course, Christmas in America has since lost its dark side. All we have now are minimum-wage mall elves. The Belsnickel is practically extinct. Disguises expire after Halloween. And although the mood has changed for many reasons, you can probably thank—or blame—a New Yorker named Clement Moore for killing off our monsters.

In 1823, Moore published the poem A Visit from St Nicholas, explains Nissenbaum, and introduced Americans to a fat new elf known as Santa Claus. Like a Christmas monster, Santa broke into people’s houses, but only to leave presents. His face was still covered, but with soot from the chimney. He didn’t take anything or disturb anybody, and he would soon eclipse all other Christmas characters, teaching Americans with a silent “wink of his eye and twist of his head” that there is nothing to dread at Christmastime.

Today, some hope to restore dread to Christmas by importing the Krampus to unlikely new homes like Los Angeles. But bloody masks, flaming torches and whippings may not be necessary; nearly half of all Americans already feel stressed by the mere thought of giving or receiving Christmas gifts.