Carol Rhodes, older sister of Lily Rhodes (the future Lily van der Woodsen, played by Kelly Rutherford on Gossip Girl), has been cast on the show's upcoming '80s spinoff.

Veronica Mars and Gilmore Girls alum Krysten Ritter has signed on to play Carol, the troubled older sister of Lily. She's described as sweet, but also a bit of a disaster who makes bad decisions. Lily moves in with Carol after a falling out with their parents.

The spinoff will be introduced May 11 as part of a Gossip Girl episode.

As for the role of Lily, EW's Michael Ausiello says that if Gossip Girl producers Stephanie Savage and Josh Schwartz end up getting their first choice to portray Lily, there will be a lot of very happy fans out there. What - and who - do you think that means?

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