Nope, unless they change it this year, which is probably unlikely as it would have bene mentione don the front page. Not every event has to come with epics! Enjoy the pressies under the tree and kick that Greenches butt!
Is there a holiday boss for the Winter Veil holiday event like there is for brewfest or halloween?
Is there any way to get epic loot?
The Abominable Greench. He's not instanced, he's a world boss. The daily quest rewards a Stolen Present, which usually contains toys, can contain a coal elemental pet and once in a blue moon has a dagger shaped like a Christmas tree.