Avatar: The Last Airbender (abbreviated as ATLA), also known as Avatar: The Legend of Aang in some regions, is an American animated fantasy action television series created by Michael Dante DiMartino and Bryan Konietzko and produced by Nickelodeon Animation Studio.

Avatar: The Last Airbender was a ratings success and received acclaim from critics for its characters, cultural references, art direction, voice acting, soundtrack, humor, and themes. The series' themes include concepts rarely touched on in youth entertainment, including war, genocide, imperialism, totalitarianism, indoctrination and free choice. It won five Annie Awards, a Genesis Award, a Primetime Emmy Award, a Kids' Choice Award, and a Peabody Award. The show is regarded by many critics as one of the greatest animated television series of all time.

Avatar aired on Nickelodeon for three seasons, from February 2005 to July 2008. The extended Avatar franchise includes an ongoing comics series, a prequel novel series, an animated sequel series, and a live-action film, as well as a live-action remake series produced for Netflix. The complete series was released on Blu-ray in June 2018 in honor of the tenth anniversary of its finale and was made available to stream on Netflix in the United States and Canada in May 2020, on Paramount+ in June 2020, and on Amazon Prime Video in January 2021.