According to Variety, Lena Headey has been cast as the queen opposite Gerard Butler in helmer Zach Snyder's 300, which Hollywood Gang Prods. and Atmosphere Pictures are producing for Warner Bros. Pictures.

Production begins Oct. 17 in Montreal, where Snyder (Dawn of the Dead) will shoot actors in front of a green screen, relying on all CG backgrounds.

Based on Frank Miller's graphic novel of the same name, film is about the real-life battle of Thermopylae, in which King Leonidas (Butler) and 300 Spartan warriors fought to the death against the massive Persian army. According to lore, their bravery led to Greece uniting and giving rise to democracy.

Headey ("Imagine You and Me," The Brothers Grimm) will play the role of Gorgo, Leonidas' wife.

Also joining the cast are David Wenham, Dominic West, Vincent Regan and Rodrigo Santoro.

Producers are Atmosphere's Mark Canton and Hollywood Gang's Gianni Nunnari, along with Bernie Goldmann and Jeffrey Silver. Miller, Deborah Snyder and Craig Flores are exec producing.

Snyder and writing partner Kurt Johnstad adapted Miller's book, with Michael Gordon penning a previous draft of the screenplay.