The 13 Yule Lads, their mother Grýla, and the Yule Cat are all members of the same family of trolls associated with Icelandic folklore. They are typically mountain-dwelling, but during the Christmas season, they sometimes visit human settlements, and while some are friendly, others are not. If you're planning to visit Iceland during the holiday season, it's a good idea to learn about these characters and how to avoid ending up on their Christmas buffet. You can also learn the proper procedures for getting the yule lads to bring presents to children.