The Yule Cat

From Harry Potter, I learned that a gift of clothing could free a house elf, like Dobby. A parallel exists in Icelandic Christmas folklore. The Yule Cat, a pet of Gryla and her Lads, prowls about looking for people who haven't been given new clothes before Christmas Eve. Like the Lads, the Cat began as a means of encouraging workers to finish processing the autumn wool before Christmas. If completed, the workers would receive clothing as a reward. If they failed, they could be eaten by the Cat. Unlike the Lads, the Cat seems to have retained a monstrous presence.

From: http://petslady.com/article/iceland-s-creepy-christmas-cat-ready-rock-reykjavik