Outside a Chippendale show you’ll never see this many half-clad beefcakes in a single gander. But this is no erotic spectacle — at least, not intentionally. No, this adaptation of Frank Miller’s graphic novel details the historic stand of the 300 Spartans of the title against the massive Persian army in 480 BC. Miller, creator of Sin City, fashioned the epic after the 1962 sword-and-sandal drama The 300 Spartans. The upgrade gets a boost from Gerard Butler as the dutiful Spartan king, Leonidas, and from Lena Headey, who adds a splash of fire as his wife. Not that director Zack Snyder shows much interest in them as he twists the brawn and battle into a cartoonish FX extravaganza with severed body parts and globules of blood flying across the screen. It makes an impression, granted, as does Xerxes (Rodrigo Santoro): seven feet tall, and more drag queen than king. He and his minions have created a regime that one Spartan tags a rule of “mysticism and tyranny.” Sounds a little like the one we’re living under today.