Jabarkan Pemilihan pelakon dari The Last Airbender dalam bahasa melayu

M. Night Shyamalan originally offered the roles of Aang to Noah Ringer; Sokka to Jackson Rathbone; Katara to Nicola Peltz; and Zuko to Jesse McCartney. In an interview with People, Shyamalan claimed that he did not want to make The Last Airbender without Nicola Peltz, "I said that only once before in my career, and that was when I met Haley in The Sixth Sense auditions." In February 2009, Dev Patel replaced Jesse McCartney, whose tour dates conflicted with a boot camp scheduled for the cast to train in martial arts. Katharine Houghton and Seychelle Gabriel played "Gran Gran", the grandmother of Katara and Sokka, and Princess Yue, another of Sokka's love interests and princess of the Northern Water Tribe, respectively. Isaac Jin Solstein played an earthbending boy. Aasif Mandvi played Commander Zhao, Cliff Curtis played Fire Lord Ozai, and Keong Sim was cast in the role of an Earthbender.

Ringer, yang tidak pernahworked on a film, mula practising Taekwondo, seni mempertahankan diri dan sukan kebangsaan Korea Selatan, pada usia 10. His skills later garnered accolades, including the title of American Taekwondo Association Juara Negeri Texas. Since Aang was bald in the animated series, pelakon yang memainkan watak tersebut perlu mencukur kepalanya, atau memakai "bald wig". Walau bagaimana pun, Ringer mula mencukur kepalanya semasa latihan mempertahankan diri untuk membantu menyejukkan dirinya, menyebabkan para penggemar dan gurunya, yang kesemuanya penggemar siri kartun, untuk memanggilnya "Avatar". Feeling the connection with the martial arts sequences from the series, Ringer heard about the film adaptation and, with the help of his instructor, submitted an audition tape. His painted blue arrow on his already shaved head helped secure him the lead role. Having not acted before, Ringer was required to attend acting school a month before filming commenced, calling the film a great experience. Peltz was familiar with the Waterbending character before submitting for the part of Katara, having faithfully watched Avatar: The Last Airbender, the animated series on which the film is based, with her younger twin brothers. She describes her character as being a big role model with young girls and women, "She’s really mentally and physically strong, strong-willed and -minded, but she’s also caring and compassionate... The movie has a lot of values, but it’s also fun. It’s fantasy, but it’s also a really cool battle between good and evil." She explained that she initially didn't know about Rathbone starring in the Twilight films until after she met him and said that working with Shyamalan was an amazing experience. Rathbone, who originally auditioned for the role of Zuko, was approached by Shyamalan to audition for the film. After waiting for six months, he received a call informing him that he was cast as Sokka. Rathbone stated that his favorite scenes were the fight sequences, which he prepared for by stickfighting.

Before Slumdog Millionaire was released, Patel auditioned for the role of Zuko by submitting a tape to the studio. Shyamalan called Patel personally to inform him that he got the part. Training for the film was intense, as he had to learn Wushu and different martial arts. Patel's first fight scene filmed called for him to be in a tub of water on a ship; he was to look at a picture of his family, which would give him the urge to fight. Patel recalls fighting, punching, and throwing and said it was truly amazing. While he was filming Slumdog in India, he would finish a take and turn one of the channels over to the animated series. Even though it is based on a cartoon, he wanted to bring as much of himself as possible to the character he was portraying. Shaun Toub, who was cast as Uncle Iroh, describes his character in the first film as "loose" and "free". He compares Zuko's "obsession" to his childhood memories and how kids are always looking for their parents’ approval, saying that Zuko just wants his father's. "He isn’t necessarily bad, he just has a great deal of built up anger and forgets to consider others. I think people will understand that he’s not bad, he’s just angry and hurting because he really wants his father to love him, but his father is too busy with other things." He says that Patel is an "18 year old with all this energy," and that Patel was able to influence him into appreciating the business of film making more. While comparing the animated series to the film, he says the film is much more serious. He attributed this change to the director trying to relate to every age group, rather than just kids.