With William van der Woodsen set to make his Gossip Girl debut, speculation is running rampant over how the character played by William Baldwin will impact the Upper East Siders.

Gossip Girl executive producer Stephanie Savage, who said the season is building to some OMG moments, says his effect on Serena, Eric and Lily will be profound and far-reaching:

"When you think about the Humphreys and Van Der Woodsens and that extended family that they have, [Serena's father] coming back really lands on everybody in a great way."

"It definitely causes major drama for Serena and Eric and the other kids, and there's an adult component with Rufus and Lily, because there's some significant backstory there."

Rufus, Lily and William: A love triangle in the making.

And according to Matthew Settle (Rufus), Billy Baldwin as Papa Dr. van der Woodsen is a great addition to Gossip Girl. Settle told E! News at the G-Star Raw event in New York City:

"It's a great love triangle. Billy's got a great energy; he's a good actor. It's believable that he would be Serena's father, and he's a great fit for the show. It's really good casting."

One long-lost family member we've seen the last of for now? Scott. "[He's] done for this season," Stephanie dished. "But he can absolutely come back at some point next season."

Are you excited to meet Dr. van der Woodsen? How will he be received by the kids he's been absent from for so long - and by his former wife? Share your theories and thoughts!

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