aang talks to 4 past avatars. the one we all know, avatar roku, the avatar before aang. then he meets avatar kyoshi, the avatar before roku. she created kyoshi island. we see her in 2 episodes "the warriors of kyoshi" and "avatar day". then he meets a water tribe avatar, avatar kuruk. he is the avatar before kyoshi. we have never seen him in any other episodes. we only see him in a game called "escape from the spirit world". when aang still couldnt decide to kill the firelord, he had to talk to an air nomad avatar, avatar yangchen. we have only seen her in "escape from the spirit world"