So what events are taking place? Oh, how about all of them. Relics of the Gree kicks off on December 8th, which is also when players can log in for rewards for the fourth anniversary of the game. The Rakghoul Plague event and Life Day celebrations both start on December 15th, which means that flesh-eating ghouls may be gathering around your Life Day meals. (Let them have their own tables.) Bounty Contract Week kicks off on December 22nd, but double XP is starting up on December 18th and running until January. It’s a month full of stuff to do, with celebrations to be had and enemies to lightsaber right in the face. What more could you want?
Star Wars: The Old Republic? If your answer is “no,” the good news is that you have a little time to become ready, as the multitude of in-game events for December aren’t getting underway until December 8th. But once they do start up, they aren’t stopping until January.
Source: Official Forums