David E. Kelley is doing the only humane thing — he's putting Ally McBeal out of its misery. The prolific producer announced on Wednesday that his Fox dramedy — which has struggled in the ratings this year — would not return for a sixth season in the fall. "It's sad to say goodbye to something you love, even when perhaps it is time," Kelley said. If Fox is smart, they'll lure Robert Downey Jr. back for the final episode — slated to air on May 20. "There are no plans for Mr. Downey to return," a show rep says.