Smallville’s upcoming Justice Society-themed two-parter has added another headliner. Executive producer Kelly Souders confirms that the highly anticipated episodes (titled “Society” and slated to air in early 2010) will mark the return of Phil Morris as Martian Manhunter (J’onn J’onzz).

As we told you before, “Society” is penned by comic book hero Geoff Johns, and marks the arrival of Justice Society members Hawkman, Doctor Fate, and Stargirl.

The abundance of special guest stars is what prompted Souders and fellow showrunner Brian Peterson to expand the episode into two parts.

“To be honest, there were so many characters and so much great story that people would’ve been robbed of some great moments if we kept it to just one hour,” says Sounders. “So now that it’s a two-parter, you won’t miss anything.”