The e-Reader was a peripheral released for the Game Boy Advance in 2002 that unlocks special content for certain Game Boy Advance and GameCube games. Content includes mini-games, different worlds, or full and complete NES games. The content was added or unlocked by purchasing e-Reader cards and swiping them in.

Among others, Pokémon Battle Arena and Animal Crossing cards were released. The Pokémon Battle Arena cards allowed you to fight a large amount of predetermined battles for Pokémon Ruby and Sapphire, whereas the Animal Crossing cards were used for the GameCube version of Animal Crossing and unlocked gifts.

In Spring 2004, Nintendo discontinued the e-Reader outside of Japan due to low sales. However, it was supported in Japan until September 2008. The Game Boy Advance family was discontinued a year later.