Jinju

Jinju was an Air Nomadic boy who lived in the Southern Air Temple before the Hundred Year War. Roughly as old as Aang, he was apparently one of the less popular boys at the temple and was often picked last for team sports, probably due to his odd behavior toward the other children and his unkempt appearance.

History
Not long before Aang froze himself in the iceberg, he created and taught his peers a new airbending trick, the air scooter, which was a sphere of air upon which one could ride, and the other children soon created an accompanying game. When Aang asked to play, he was denied due to the fact that he was the Avatar, giving his team an unfair advantage. As Aang left, Jinju was picked last to play on one of the teams.

Like the rest of Air Nomads, Jinju did not live to see Avatar Aang bring an end to the War that had begun with the Air Nomad Genocide by the Fire Nation.

Trivia

 * Jinju is the only other named Air Nomad child besides Aang.