The Zack Snyder and Kurt Johnstad-scripted 300 spin-off has (at least temporarily) abandoned its previous title, 300: Battle of Artemisia, and is seemingly in a state of flux, going off previous reports that the filmmakers behind the project are still determining its position in relation to Snyder's original Frank Miller comic book adaptation.
Sullivan Stapleton was the only actor officially attached to the project, but a new casting update has revealed that another lesser-known actor (whose starmeter is also slowly, but steadily on the rise) has likewise landed one of the film's more pivotal parts. However, that hot-off-the-press scoop also refers to the project as a sequel to 300, which seems to contradict the long-held presumption that this flick is based primarily on Miller's prequel comic series (titled Xerxes).
Jamie Blackley, a costar of such films as London Boulevard and the upcoming Snow White and the Huntsman is the new addition to the 300 spin-off. Deadline describes the actor's part in the movie as being that of Calisto, a teenager who is driven by a "desire to become the heroic man/soldier his father was" and eventually ends up commanding a small battalion of (Greek? Persian?) warriors.
Eva Green is still said to be negotiating to join the film as the conniving Artemisia, who seeks to improve her own fortunes by manipulating the power-hungry Xerxes into declaring war against the Greeks. When Stapleton initially signed on, he was reported to have landed the part of the aforementioned Persian leader (a role filled by Rodrigo Santoro in 300) but those claims were later retracted. The actor's part remains officially unknown, for the time being.
Warner Bros.' plan all along has been to cast either unknown or non-A-list stars in the 300 spin-off - in part so as to potentially jump-start their careers (like the original film did for people such as Gerard Butler, Lena Headey, and Michael Fassbender), but also because this film is a smaller-profile undertaking with a relatively untested director in Noam Murro (Smart People) sitting at the helm. So, while the project's status as either a sequel or a prequel may still be officially unsettled, the movie's pre-production process otherwise remains right on track.
We will continue to keep you posted on the 300 spin-off's development as more information is released.