Behind the Scenes
Tars Tarkas and the other Tharks were one of the major hurdles the John Carter story had in going from page to screen over the years. In the film, he is achieved with motion capture technology applied to a stilt equipped Willem Dafoe. Arm extensions were also used to further get the effect of his longer arms and secondary crew members helped provide reference for the second set of arms in tandem with Dafoe's performance.
Following Thark customs of "survival of the fittest", Tars has to act in his expected role as being a tough strong leader who shuns any weakness. However, he has great capacity for compassion and caring, which he often must hide for the sake of maintaining his position in the tribe. When he first meets John Carter, he sees him as a potential new ally in battles against other tribes, but is willing to let him go to try and find his path home. But this opened him up to being overthrown and afterwards he is demoralized until finding strength in the realization that his daughter is alive and Carter pointing him to his own philosophy that a Thark can succeed as long as he has one arm.
Tars Tarkas first appears in the film shortly after John's arrival, finding the Thern medallion that transported him to Barsoom. Traveling with a contingent of soldiers to the Thark hatcheries, he tries to talk with Carter in Barsoomian, believing Carter's name is "Virginia" in the process. When seeing his incredible jumping ability, he chooses to take him back to his village alive. Carter's stubbornness proves difficult in selling his usefulness to the village until Carter gradually picks up the ability to speak Barsoomian and makes a daring attack on the Zodangan fleet to rescue Dejah Thoris. In honor of his success Tarkas gives John Carter the title of Dotar Sojat or "His Right Arms". Carter still refuses to be a soldier for any particular cause and after discovering he seeks to steal back the medallion and put Sola in danger of blasphemy for entering and potentially desecrating the local temple, allows Carter and Thoris to leave, taking Sola with them to keep her from execution while allowing her to make a pilgrimage to the Barsoom afterlife along the river Issus.
When Carter later returns to build an army to take out Zodanga and stop a final assault on Helium, he finds Tars Tarkas has been overthrown by Tal Hajus and imprisoned and set for execution by the White Apes in the arena. Carter and Sola manage to awaken his broken spirit and upon killing the White Apes and Hajus, Carter rallies the Tharks together to assault Zodanga. Upon finding the city has been mostly emptied and the warriors on their way to Helium, Carter is forced to fly alone until the Tharks lead by Tarkas and Sola decide to break their flying taboo and follow him. They succeed in defeating Sab Than and the Zodangans, as well as forcing Matai Shang to leave Barsoom for good, saving Deja, Barsoom and creating a new alliance between the Tharks and the Red Martians to help Barsoom down the line.