Aang (Zachary Tyler Eisen) is the fun-loving, 112-year-old protagonist of the series, who is biologically twelve years old but was frozen in an iceberg for one hundred years. He is the current incarnation of the Avatar, the spirit of the world manifested into human form, whose duty is to maintain balance among the nations of the world. Aang is a reluctant hero, who would prefer adventure over his job as the Avatar and making friends over fighting the Fire Nation.

Air Nomads

Toph Beifong (Jessie Flower) is a twelve-year-old blind earthbender. In Book Two, she leaves her wealthy family and comfortable home to join Aang on his quest, with a plan to teach him earthbending. Though blind, Toph "sees" by feeling the vibrations in the ground through her feet. She becomes the first earthbender to learn to bend metal and is considered one of the most powerful earthbenders in the world.

Earth Kingdom

Sokka (Jack DeSena) is a fifteen-year-old warrior of the Southern Water Tribe. With his sister Katara, he accompanies Aang on his quest to defeat the Fire Lord. The joker of the group, Sokka describes himself as "meat-loving" and "sarcastic". Unlike his companions, Sokka cannot bend an element, but the series, though it often makes him the victim of comedy at his expense, frequently grants him opportunities to use his ingenuity and weapons, including his trusty boomerang, a battle club, and a sword he forged from a meteorite.

South Water Tribe

Zuko (Dante Basco) is the sixteen-year-old exiled prince of the Fire Nation and original main antagonist of the series. Due to events in Zuko's past, his father, Fire Lord Ozai, deems him a complete failure, and Zuko feels he must capture the Avatar to regain his honor. Over time, Zuko struggles to deal with his anger, self-pity, and familial relationships; meanwhile, he grows sympathetic to the peoples his nation has terrorized. In Book Three, he defects from the Fire Nation and joins Aang and the team in order to teach Aang firebending. At the end of the series, he is crowned ruler of the Fire Nation.

Fire Nation

Katara (Mae Whitman) is a fourteen-year-old female waterbender of the Southern Water Tribe, the only waterbender in the tribe. Katara discovers and frees Aang from an iceberg in which he had been trapped for a hundred years. With her fifteen-year-old brother Sokka, she accompanies Aang on his quest to defeat the Fire Lord and bring peace to the world. In the original unaired pilot episode, Katara was known as Kya; this name was later used for her mother.

South Water Tribe