This Christmas critter takes second billing to his compadres, the 13 Yuletide Lads, but he's pretty interesting in and of himself. You see, the Yuletide Cat is the enforcer of Icelandic Christmases. While the Lads, who have names like Sausage Snatcher and Door Sniffer, take turns generally tormenting innocent folk, the Cat figures out which children have not received new clothing.
You see, hard workers need new clothes. Lazy ones don't. Neither do bad ones. And the story varies in severity as to whether the Cat only steals their presents, or goes so far as to eat those children.
Here's a colorful and detailed page on the Yuletide Lads that includes the Cat -- scroll down to the bottom to see playing cards with his image. (For the rest of the lads click "1" at page bottom.)
For a bit more of the story, here's somebody's cute craft project.
(2012: In 2011 I found more stuff on the Yuletide Cat, and here's that post! Happy Yuletide.)