When last we saw our favorite Upper East Siders, Serena van der Woodsen was embarking on a new quest, with the aid of Carter Baizen - to find her dad.

The mystery man who fathered the blond bombshell and her brother, Eric, has never been seen on the show, save for the '80s scenes in "Valley Girls."

Will he be a presence on the show next season in the present time?

With all the other exciting (and controversial) Gossip Girl cast additions this week (Hilary Duff, Joanna Garcia), who might play this paternal part?

"Brad Pitt," Blake Lively exclaimed when E! News asked her about it at the CW upfronts. "Or maybe [he should be cast] as my new boyfriend."

Don't hold your breath, Blake. Her on-screen brother, Connor Paolo, said:

"We've been asking since day one who daddy dearest is, so it'll be good to find out. I'd say Christopher Walken could make a great dad. I think [his and Lily's] dynamic would be awesome. I'll push that one. Or maybe Jack Nicholson."

At 72, isn't Jack a little old? Maybe he should be their grandpa?

"I think, with Lily, he could be dad," he asserted.

Fair point, Connor.

Who do you think should play Eric van der Woodsen on Gossip Girl? Any ideas? Let us know what you think by leaving comments below.

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.