A new girl is coming to New Girl.

The Fox sitcom has cast Linda Cardellini (forever beloved for her role in Freaks and Geeks, most recently seen in Mad Men) as Jess' sister, Abby, described by network sources as a "wild child" who will stick around for a few weeks.

New Girl Season 3 resumes on January 7, though Cardellini's debut date is unknown.

In the meantime, remember: you can watch New Girl online!

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.