Costar couple! January Jones is dating her fellow Last Man on Earth star Will Forte, Us Weekly can exclusively reveal.

A source tells Us Weekly that the Mad Men actress, 37, has been casually dating the Saturday Night Live alum, 44, for a couple of months. "He's a good guy," the insider tells Us, adding that the new couple is "having fun."

Jones, who is the mother to one son Xander, 3, has never been married. She previously dated director Noah Miller, splitting from the Sweetwater writer in January 2013. Her dating history also includes relationships with Jason Sudeikis, Ashton Kutcher, and Josh Groban.

Forte has never been married either, and boasts a surprisingly slim relationship history. In his years of fame, Forte has never stepped out with a confirmed girlfriend.

"I'm kind of under the radar," Forte told The A.V. Club in 2010. "Not a lot of people notice me. Which is surprising, because I'm so sexy. They're probably intimidated by my sexiness and crushability."

The newly linked lovebirds hit the small screen together earlier this month in Fox's The Last Man on Earth. Forte and Jones star in the apocalyptic comedy alongside Kristen Schaal.