Given that it was a rough habitat to settle, it's unsurprising that Iceland's folklore isn't exactly warm and fuzzy. In fact, their first stories are almost as horrific as the Brothers Grimm fairytales. Even Icelandic children were not sheltered from the rougher aspects of life. During the Christmas season, for example, the youngest children were told creepy tales of the Yule Lads.
Accompanied by their mother Gryla and the demonic Yule Cat, the Yule Lads prowled during the Christmas season. Children unlucky enough to be kidnapped by them were cooked alive and eaten.
The Yule Lads had many iterations over the years and were eventually immortalized in a poem that's still memorized in Icelandic schools. However, the original story of these scary Christmas creatures was so terrible that it was eventually banned altogether.
After hearing the tale of these morbid elfin lads, any childhood fears you had of Santa Clause will seem pretty silly.