Because there can never be enough reasons to threaten the relationship between Leonard and Penny, right? 'The Big Bang Theory' will air its latest Halloween-themed episode tonight with "The Holographic Excitation" but it's Leonard who should really be scared. Upcoming episodes will see the introduction of a character from 'Mad Men' and 'Alphas' star Ryan Cartwright, one who might be in a position to put a dent in the newly reinstated couple's relationship. But is he all talk?

It seems 'The Big Bang Theory' might be getting a bit smarter in its sixth season, as Penny (Kaley Cuoco) is headed back to school. But where we imagine Leonard (Johnny Galecki) being thrilled with that idea, he's probably not so on board with her charming new English study-buddy, courtesy of former 'Mad Men' and current 'Alphas' star Ryan Cartwright!

The Hollywood Reporter first confirmed the casting, revealing that Cartwright would appear in the November 15 episode as Cole, becoming chummy with Leonard's newly re-sworn girlfriend a little too quick for comfort.  The real question is, will Penny's new-found academia stick?

"She's an aspiring actress and she's been here for four or five years now and got that one commercial but nothing huge happened," Exec Producer Steve Molaro said. "We would like to see more for Penny and I think that's something where we're all thinking about and discussing, whether it's on the acting side or some other avenue. We definitely would like to expand Penny's life."

What say you? Can Penny and Leonard handle another obstacle? What's next for 'The Big Bang Theory' season 6?