Thomas Haden Church, rumored to be Tars Tarkas not long ago, has been confirmed in Pixar’s John Carter of Mars as Tal Hajus, one of the evil Green Martian Tharks. He was the Jeddak when John carter first came to Mars and is eventually killed by Tars Tarkas. But the synopsis for the character given says he is “an ambitious and vicious Thark warrior who is biding his time to be a ruler.” Does that mean a plot change?
Also joining the cast is Mark Strong as Matai Shang, leader of the Holy Therns (the White Martians) I believe they are only in the second and third books (I don’t remember them in the first, but I could be wrong) so there is either foreshadowing, or they are combining stories and making it way confusing.
The third new name is James Purefoy as Kantos Kan, the Red Martian John Carter befriends while stuck in a gladiator-like event, who is a captain in the Helium (a Red Martian city) army.