Gossip Girl Spoilers: Who's that lady from the cemetery?!

During the last episode, Chuck saw a woman walking away from his father's grave who seemed to know who he was. Ausiello has the spoilers on the identity of this woman and here they are!

Question: Who was she the woman standing over Bart’s grave on Gossip Girl? Was it Chuck’s mom? –Randi
Ausiello:
First off, the grave stalker has a name, and it’s Laura Harring (The Shield). Second, yes, she will reveal herself to be the Bass family matriarch when GG returns in March. Something about this makes my impostor antennae go up though. Call me a whore for stunt casting, but if and when Chuck’s mum returned from the dead, I always imagined producers would go for a big name. You know, like Michelle Forbes. Who’s with me?

Source: Ausiello