Radar reports that our favorite box office trailblazer, Josh Hartnett, has finally given up hope of nailing zingers on 30 Rock or appearing in a mildly successful movie and moved on to simpler pursuits: the London theater. In a role that will certainly pay homage to Tom Cruise’s former career as an actor, Hartnett will appear as Rain Man’s Charlie Babbit opposite a less-heartthrobby Brit filling Dustin Hoffman’s pigeon-toed shoes. Most interesting of all? Hartnett manages to say, “It has always been my intent to work on the London stage,” without laughing. But the bigger question remains (ahem, Katie Holmes): why do movie stars assume tackling the theater will be a breezy little side-job guaranteed to build acting cred? The track records of Julia Roberts, Denzel Washington, and David Schwimmer beg to differ, after the jump.