It was reported back in February that British actor Jamie Blackley would play Callisto - apparently one of the lead roles - in the follow up to 300. But now HeyUguys report..
“Blackley, who was cast as a co-lead in the film has now been dropped from the production altogether in favour of their original choice for the role.”
No idea who that original choice might be, but Warner Bros./Legendary will most likely follow this news up with something official soon. The character of Callisto is described as
"a teen whose desire to become the heroic man/soldier his father was leads the 16-year-old to become a leader of a small band of soldiers".. Blackley will appear next in
Snow White And The Huntsman
300: Battle For Artemisia is set for release August, 2013 and (still) stars Eva Green and Rodrigo Santoro.