As of 2015, 61 episodes of "Avatar: The Last Airbender" exist. The episodes were split across three seasons, with the first two seasons consisting of 20 episodes, and the third consisting of 21 episodes.
The 61 episodes of "Avatar: The Last Airbender" aired on Nickelodeon from Feb. 21, 2005, to July 19, 2008. The series, particularly the second and third seasons, received critical acclaim, with praise for the show's animation, fight choreography and handling of mature themes. A sequel series, "Avatar: The Legend of Korra," aired 52 episodes over four seasons, from April 14, 2012, to Dec. 19, 2014. The sequel series also received critical acclaim.