Wizards of the Coast
Since 2006, Wizards of the Coast has been giving out holiday Magic: The Gathering promo cards annually at their parties, and this year, the company has revealed the holiday card for this year: Bog Humbugs. Check it out:

This is the thirteenth Magic: The Gathering holiday promo card, and as you can see below its ability text, there's a sheet music for Jingle Bells and I think it's a nice touch. It's nice to see a black promo card made for a colorful season.
Holiday cards are tournament-prohibited, silver-bordered cards just like the cards in the Un-sets. They are given out to members of Wizards internal teams as well as business partners. Unlike most Magic cards, you won't find this in any booster pack or any other Magic product but you can probably find one on eBay.
Here's the full list of holiday Magic promo cards:
Related: Magic Community & Wizards of the Coast Helped The Library Kids Get a Full Prerelease Experience