MGM has closed a deal with Dwayne Johnson to star in Brett Ratner’s “Hercules,” which will start production this October in New Zealand.Studio confirmed Johnson’s casting nearly two weeks after Variety first reported that the former WWE star was in talks for the coveted action role. Scribe Ryan Condal adapted Steve Moore’s graphic novel “Hercules: The Thracian War,” which debuted in May 2008 via Radical Publishing. MGM’s Roger Birnbaum, Gary Barber and Jonathan Glickman will produce with Peter Berg and his Film 44 partner Sarah Aubrey, as well as Barry Levine of Radical Pictures, whose Jesse Berger will exec produce. Over the last several years, Johnson has emerged as one of Hollywood’s leading action stars. He co-starred in “Fast Five,” the highest-grossing film in the “Fast and Furious” franchise, and he currently toplines “Journey 2: The Mysterious Island,” which is already outperforming the worldwide gross of the original pic starring Brendan Fraser. Thesp, who’s currently prepping for his role as a law-breaking bodybuilder in Michael Bay’s “Pain and Gain,” next stars in Paramount’s action sequel “G.I. Joe: Retaliation.” Johnson is repped by WME.