Long ago, the Four Nations lived together in harmony. Then, everything changed when the Fire Nation attacked. Only the Avatar, master of all four elements, could stop them. But when the world needed him most, he vanished.
A hundred years passed, and my brother and I discovered the new Avatar, an airbender named Aang. The problem is, this Avatar is still a kid, and although his airbending skills are great, he has a lot to learn before he's ready to save anyone.
But I believe Aang can save the world.
Avatar: The Last Airbender is a Nicktoon that ran from 2005-2008 on Nickelodeon. It is the first series in an eponymous franchise which takes place in a Constructed World divided into four nations: the Water Tribes, the Earth Kingdom, the Fire Nation, and the Air Nomads. Each nation has developed a spiritual art form to manipulate ("bend") their namesake element, but only the Avatar — one person reincarnated periodically into each race — is capable of mastering all four elements. The Avatar's role is to serve as a peacekeeper and protector for all four nations (as well as bridging and balancing the physical and spiritual worlds).
The show's story centers around Aang, the biologically-12 (chronologically 112) year-old incarnation of the current Avatar, and the eponymous Last Airbender. He must master the four bending arts so that he can save the world from Fire Lord Ozai and end the century-long war, a war which he accidentally avoided, spending a hundred years trapped in an iceberg after running away from his sudden heavy responsibility as the Avatar. Ozai's plans for domination are on a specific timetable, though, meaning that Aang has until the end of summer to stop them.
Aang has thankfully found himself in good company with teenage waterbender Katara and her brother Sokka, the two who freed Aang from the iceberg. As the trio works to save the four nations with the company of Aang's lemur and flying bison, they gain many more allies; take a look at the Character Sheet to get to know more about the cast.
Due to the sheer number of trope examples, they have been divided into their own alphabetized pages. There is also a largely-complete recap page available for those who want to see what all the fuss is about.