Avatar is set in a largely Asian-inspired world in which some people can telekinetically manipulate one of the four elements—water, earth, fire or air—through practices known as "bending", inspired by Chinese martial arts.

The series also follows Zuko—the exiled prince of the Fire Nation, seeking to restore his lost honor by capturing Aang, accompanied by his uncle Iroh—and later, his sister Azula.

Avatar: The Last Airbender was a ratings success and received widespread acclaim from critics and audiences, with high praise for its characters, cultural references, art direction, voice acting, soundtrack, humor, ending, and thematic content.

In the first season, Aang travels with Katara and Sokka to the Northern Water Tribe so he can learn waterbending and be prepared to defeat the Fire Nation.

Prince Zuko, the banished son of the current Fire Lord Ozai, pursues them, accompanied by his uncle Iroh, hoping to capture the Avatar in order to restore his honor.

Zuko and Iroh, now fugitives from the Fire Lord, become refugees in the Earth Kingdom, eventually settling in its capital Ba Sing Se.

Aang's group travels to Ba Sing Se to seek the Earth King's support for an attack on the Fire Nation timed to an upcoming solar eclipse, during which firebenders will be powerless.

During Konietzko's stint as art director on Invader Zim, he and DiMartino formulated the idea of pitching a coming-to-age series based on their childhoods, but were too busy with their respective jobs to solidify the concept.

Upon the end of his job on Invader Zim, Konietzko met with Coleman, introduced him to DiMartino and discussed their intent to create a series that held heart and integrity while meeting the network's commercial requirements.

He added that the network was following the success of the Lord of the Rings and Harry Potter film series and was thus searching for non-violent action and adventure concepts with an emphasis on legends and lore.

Among them was a sketch that Konietzko created during his time on Invader Zim, which featured a robot cyclops monkey with an arrow on his head and holding a staff, a balding middle-aged man in a futuristic outfit, and a bipedal polar bear-dog hybrid.

[18] DiMartino drew inspiration for what would become the Southern Water Tribe from a documentary on the Imperial Trans-Antarctic Expedition, and he pitched Konietzko the idea of a group of people similarly trapped in the South Pole.

[19] Two weeks after their meeting with Coleman, Konietzko was suddenly inspired by DiMartino's idea and formulated a concept of a group of kids in the South Pole who were terrorized by "fire people" and rescued by the young nomad from his earlier drawing.

[19][21] The co-creators successfully pitched the concept to Coleman with early sketches of Aang, Katara, and Sokka, three color images depicting the desired action, adventure, and magic aspects, and a description of the series' characters, setting and full story arc.

Ehasz believed that a fourth season would be created but this plan was interrupted when Konietzko and DiMartino became occupied with assisting M. Night Shyamalan on the film The Last Airbender.

Ehasz says that Shyamalan insisted they create a fourth season instead, but Konietzko and DiMartino wanted to focus on the live-action film as they were executive producers on the project.

[20] The series addresses many topics rarely touched on in youth entertainment, including issues relating to war, genocide, imperialism, colonialism and totalitarianism, gender discrimination and female empowerment, marginalization and oppression, spirituality, as well as the philosophical questions surrounding fate, destiny, and free will.

[40] The character Zuko and his relationship with his father and Uncle Iroh is the main redemption arc of the series, and represents the show's message that destiny and fate are not binding or set by other people but can be changed.

[42] Avatar: The Last Airbender was the highest-rated animated television series in its demographic at its premiere; an average of 1.1 million viewers watched each new episode.

[45] A one-hour special, The Secret of the Fire Nation, consisting of the episodes "The Serpent's Pass" and "The Drill", aired on September 15, 2006, and attracted 4.1 million viewers.

[65] Franco "Cricket" Te of Nerd Society described Avatar: The Last Airbender as "one of the best cartoon[s]" he had ever seen, recommending the series for its characters and plot.

[68] Nicole Clark, writing for Vice News, stated that the show's narrative depth was "its greatest asset", and praised the story's "emotional authenticity" and how it "expose[d] very young viewers to darker subject matter, like genocide and authoritarianism, while giving them a framework for understanding these issues.

[69] According to Nick Hartel, the series touches on themes of "genocide and self-doubt" without frightening younger children; rogue characters are redeemable, sending an important message that people can change and are not bonded to "destiny".

[57] D. F. Smith compared the series' plot to Japanese action cartoons, calling its tone and dialogue "very American" and praising the humor leavening an epic, dramatic theme suitable for all ages.

[62] Joshua Miller called the series surprisingly dark despite its "silly" theme; the plot is livelier than that of Lost and, similar to the latter show, emphasizes character development.

He praised the action scenes as "well rendered", comparing the development of the Avatar world to that of The Lord of the Rings, and the fight choreography as "wonderful in its most minor details".

[105] The Last Airbender stars Noah Ringer as Aang, Nicola Peltz as Katara, Jackson Rathbone as Sokka, Dev Patel as Zuko, and Shaun Toub as Iroh.

Avatar: The Last Airbender – The Promise, published in three volumes in 2012, explores the fate of the Fire Nation colonies that become The Legend of Korra's United Republic.

[136] The Rift was followed by Avatar: The Last Airbender – Smoke and Shadow about a resistance force in the Fire Nation against Firelord Zuko, who at the end of the original series assumed the throne.

[137] The fifth graphic novel was Avatar: The Last Airbender – North and South, which follows the events of Smoke and Shadow and is about Katara and Sokka returning to the Water Tribe to see various changes to their homeland.