Released in the summer 2006 the Avatar: The Last Airbender LEGO theme was based on the popular Nickelodeon TV show with the same name and based on Book One of Avatar. The theme's sets were only released in the United States and Canada and with only two sets makes it one of the smallest themes. The first sets in the theme where designed to test if the theme would be commercially viable and was pitted against the other Nickelodeon theme SpongeBob. Ultimately Avatar lost in popularity and was never continued. The discontinuation of the theme is partly due to the belief that Avatar: The Last Airbender would become obsolete, as only three seasons were planned.