Top 50 Power Showrunners 2011

Since taking over showrunning duties from series creator Greg Daniels during The Office's sixth season, two-time Emmy winner Lieberstein has had his share of sleepless nights. "There's always something keeping me up," he admits. "That quality doesn't dip, that we're viable. Steve Carell leaving created a whole new set of challenges." As the series chugs along in season eight with new blood in James Spader, Jenna Fischer's real-life pregnancy and Ed Helms sitting in Carell's manager seat, Lieberstein, 44, has dealt with these curveballs while also acting on The Office -- he was hired first as a writer and producer on Office but was also cast as despised HR rep Toby -- but considers himself a writer first, having also worked on The Bernie Mac Showand The Drew Carey Show.