Gerard Butler has signed on to star in "300," the adaptation of the Frank Miller graphic novel that Zack Snyder is directing for Warner Bros. Pictures.

The film will tell the true story of 300 elite Spartan warriors led by their fearless king, Leonidas (Butler), who thwart the charge of Xerxes and his massive Persian army at the battle of Thermopylae.

The studio is looking to make the film in the style of the graphic novel, which Miller wrote and drew in 1998. Miller, known for his work on the "Batman" and "Daredevil" comics, is the creator of "Sin City," whose stylishness was rendered to the big screen by Robert Rodriguez this year. Heavy use of greenscreen and virtual sets is being mapped out but with an eye toward maintaining the look of the graphic novel.

Principal photography is to begin Oct. 17 in Montreal.

Hollywood Gang Prods.' Gianni Nunnari and Atmosphere Pictures MM's Mark Canton are producing, along with Bernie Goldmann and Jeffrey Silver.

The executive producers are Miller, Deborah Snyder and Craig J. Flores. Steve Barnett is the co-producer.

Snyder and his writing partner, Kurt Johnstad, adapted Miller's book, with a previous draft having been done by Michael Gordon.

Greg Silverman and Geoff Shaevitz oversee for Warners.

Butler starred as the Phantom in last year's "The Phantom of the Opera." His credits include "Lara Croft Tomb Raider: The Cradle of Life" and "Reign of Fire."

Butler is repped by CAA, ICM London and Alan Siegel Entertainment.