In Iceland, folklore has deep roots. Stories passed down from generation to generation about elves, trolls, giants, and other mythological creatures living in the country’s many natural wonders are still a big part of Icelandic culture. Stories surrounding Christmas are no exception—although in Iceland, things aren't always quite as jolly as the bearded man in a red suit.

Instead of Santa Claus, Iceland has the 13 Yule Lads, or Jólasveinar. According to Iceland Magazine, the Yule Lads live in undisclosed locations around the country and descend onto villages one by one during the 13 days before Christmas. These half-ogre, half-trolls are said to break into houses and terrify children while their mother, Grýla, stuffs bad kids in a sack and turns them into stew. If you're thinking this sounds gruesome, you're right, but it used to be worse: In the 18th century, according to the BBC, storytellers would compete to tell tales about the lads' violent adventures. The stories got so bloody that in 1746, the government issued a decree prohibiting parents from scaring kids with the stories of the Yule Lads, according to Atlas Obscura.

Today, the Yule Lads are pretty kind. They've been influenced by American ideas about Christmas, and like Mr. Claus, they now leave gifts rather than stealing food. However, their earlier incarnations live on. Here's what you need to know about each of the Yule Lads, listed here in the order in which they appear in town.

1. Stekkjastaur, or Sheep-Cote Clod

Stekkjastaur is said to have long, stiff legs. He sneaks onto farms and steal milk straight from the farmers' ewes. During the winter months, when the winds would blow and farmers would hear the sheep bleating, it was believed that the animals were being harassed by Stekkjastaur.

2. Giljagaur, or Gully Gawk

According to legend, this Yule Lad would hide in gullies all over town and then sneak into cow sheds to steal milk—sometimes right from the animal. While this may not seem like a big deal, in doing so Giljagaur was robbing people of a key ingredient in many Icelandic dishes.

3. Stúfur, or Stubby

Shorter than the rest of his brothers, Stúfur was infamous for stealing pots and pans containing leftover crust. This might seem harmless enough, but many families depended on leftovers to get them through the long winters, and in some cases their pots and pans might be the most valuable items they owned.

4. Þvörusleikir, or Spoon-Licker

Abnormally thin and with a self-explanatory name, Þvörusleikir would sneak into homes and lick unwashed cutlery.

5. Pottaskefill, or Pot-Scraper

Just like Þvörusleikir, Pottaskefill steals leftovers.

6. Askasleikir, or Bowl-Licker

It’s creepy enough that Askasleikir sneaks into homes in the middle of the night to lick leftovers that are in bowls. But to make matters worse, he hides under the beds of children and waits for them to fall asleep before sneaking whatever is left.

7. Hurðaskellir, or Door-Slammer

Hurðaskellir seems particularly evil. Legend has it that he would sneak into homes all across Iceland and slam doors in the middle of the night while people were trying to sleep.

8. Skyrgámur, or Skyr-Gobbler

Skyr, which is a lot like yogurt, is a key ingredient in the Icelandic diet, especially around the holidays. So you can imagine an Icelander's disappointment after waking up and finding that Skyrgámur had stolen most of it.

9. Bjúgnakrækir, or Sausage-Swiper

Starting December 20, one has to be particularly careful about keeping an eye on their smoked sausage. It's said that Bjúgnakrækir will break into people’s homes and hide in the rafters; once the coast is clear, he’ll swoop down and snatch any available sausage.

10. Gluggagægir, or Window-Peeper

As if having monsters break into your house and steal food isn't bad enough, Icelanders also had to watch for peeping in their windows. Gluggagægir not only served as a reminder for children to not go outside during the dark, cold winter months, but served as eyes for his mother, keeping track of naughty children she could steal and boil for dinner.

11. Gáttaþefur, or Door-Sniffer

This Yule Lad was known for his abnormally large nose, which he would use to sniff out baked goods. Legend has it that he was forever searching for laufabrauð, or leaf bread, a Christmas delicacy often decorated with intricate patterns.

12. Ketkrókur, or Meat Hook

Ketkrókur would lurk in different locations in the house, and when everyone was asleep, use a long hook to steal the centerpiece of the Christmas meal—meat. Unlike his brother Bjúgnakrækir, who only enjoyed smoked sausage, Gáttaþefur didn’t discriminate when it comes to his animal protein.

13. Kertasníkir, or Candle-Beggar

Like his siblings, at first the crimes of Kertasníkir, or the candle stealer, may seem harmless, but they're not. In years past, candles were a vital part of surviving the winter in Iceland, since they provided light during the long hours without sun. And Kertasníkir didn’t even use the candles. Instead, he ate the tallow they were made from. To make matters worse, rather than hiding out like his siblings, Kertasníkir stole candles right out of children’s hands.

14. Grýla

The mother of all 13 Yule Lads, the ogress Grýla is one of the oldest mythical characters in Icelandic folklore. The earliest writing about her dates back to 13th-century manuscripts. Grýla, whose name loosely translates to "growler" according to Smithsonian, is known for beating and berating her husband Leppalúði, a troll and the father of the 13 Yule Lads. According to legend, Grýla was married twice before, but she killed and ate her first husband, Gustur, and murdered her second husband, Boli.

While there's disagreement on what she looked like, one rhyme says the ogress has 15 tails, each of which holds 100 bags with 20 children. Another story claims she has 40 tails. Some poems say she has 300 heads, each of which has three eyes. Other legends claim she has eyes in the back of her head, ears that are so big they hit her nose, a beard, blackened teeth, and hooves. In other words, she's probably not someone you want to run into if you're alone in the woods.

Grýla also had a unique survival hack: It's said that she set out when winter started to look for children who had misbehaved. Once she found them, she stuffed them in a giant sack, and then took them back to her cave to boil them alive. The result was a stew she ate until next winter.