Iio

Sister Iio was an Airbender nun, and the Mother Superior of the Eastern Air Temple during Aang's childhood. She appeared in a flashback in "Appa's Lost Days".

History
Sister Iio prepared several children, including Aang, to bond with a group of young Flying Bison. She gives each of them an apple, telling them how to choose a bison carefully, because "a Sky Bison is a companion for life". She always knew best, but she was so unaffected and cheerful, that no one really minded. She was said to be a superb Air Ball player. Her ultimate fate is unknown, though she likely died when the Fire Nation attacked the Air Nomads.