Order of the White Lotus

It was revealed in the Book 3 Finale of Avatar that Iroh is a Grand Master Lotus! Also, it was revealed that Fung, the man in "The Desert" who helped Iroh and Zuko escape Xin Fu, is actually a member of the Order of the White Lotus. It is also true that every person who tried to teach Aang about being the Avatar claims to have known Monk Gyatso, who is also rumored to have been a member of the Order.