The 300 sequel, 300: Battle of Artemisia has finally cast its first male lead in the form of Sullivan Stapleton (Animal Kingdom). Stapleton will star opposite Eva Green (Casino Royale), who was in recent talks to play Artemisia, the “ruthless, gold-covered goddess who persuades Xerxes to amass his army and helps lead them into battle.” There is currently some confusion as to whether Stapleton will be cast as Xerxes (portrayed in the original 300 by Rodrigo Santoro) or if he will be portraying the lead role of Themistocles, the leader of the Greek forces who oppose the Persian army.Directed by Noam Murro (Smart People) and written/produced by 300 director Zack Snyder, 300: Battle of Artemisia takes place in a similar time as the original but will have a new setting and cast of characters. Hit the jump for more.Variety originally reported that Stapleton was cast in the 300 sequel and would be playing Themistocles. Ironically, Stapleton’s Animal Kingdom co-star Joel Edgerton was originally in talks for the role, but turned it down. Stapleton was previously unavailable due to a scheduling conflict with the TV show Strike Back, but with the sequel’s production being delayed until summer, Warner Bros and Legendary Pictures were able to work things out.Deadline, however, is reporting that Stapleton will play Xerxes, the leader of the Persian armies. Though touted as a prequel to 300, the filmmakers are reportedly still deciding its positioning and have not yet deemed it a prequel nor a sequel.Which ever role Stapleton will end up playing, he can next be seen in The Gangster Squad, from director Ruben Fleischer (Zombieland). The period picture about the LAPD vs the Mafia in the 1940s and 1950s also stars Sean Penn (Mystic River), Ryan Gosling (Drive) and Emma Stone (The Help) and hits theaters on October 19^th.