Margo Harshman

There's a new girl in town on The Big Bang Theory — and that might mean trouble for Leonard and Penny.

Margo Harshman, who previously starred on NBC's Bent, is joining the CBS comedy as Sheldon's (Jim Parsons) new assistant, Alex, TVLine reports.

The Big Bang Theory Season 6 promo: Are Sheldon and Amy breaking up?

Despite her professional relationship with Sheldon, she sets her eyes on Leonard (Johnny Galecki), which may drive a wedge between him and Penny (Kaley Cuoco), according to the report. Executive producers Bill Prady and Steve Molaro told TVGuide.com earlier this summer that the couple is "on a very rocky road."

Sounds like it's about to get rockier!

The Big Bang Theory premieres Thursday, Sept. 27 at 8/7c.