This page describes the relevant show characters and what happened to them after the finale of Avatar: The Last Airbender.
Aang
Aang takes Ozai’s bending, but being frozen in the iceberg takes a toll on his body quicker than it happened in Legend of Korra, which would lead to his eventual death. Upon Aang’s death, Appa was by his side and passed along with him. Momo still flies around the Southern Air Temple, an old but still mischievous, lemur. On a rare occasion, he can be spotted.
Ozai †
He ends up in prison but succumbs to disease and dies.
Team Avatar
For a short time after Aang’s death, Katara, Sokka, Suki, Toph, and Momo continued to travel together. But as Zuko was brought home to transition the role of Fire Lord to the rightful heir Seb, each of the other members of Team Avatar eventually went off to fulfill their own responsibilities
Katara
She returned to the Water Tribes to become a bending teacher and healer. She still teaches other waterbenders the art of healing.
Sokka & Suki
They both continued to live their warrior lives for a while. Sokka trained the Southern Water Tribe military and Suki mentored the next the Kyoshi Warriors. They kept a relationship together and eventually left their responsibilities as trainers to form a family in a remote village of the Southern Water Tribe, where they happily live now.
Toph
She mentors a couple students in metalbending to mastery level before working with Earthen-Fire Industries. Her students’ whereabouts are unknown.
Zuko & Mai
After returning to the Fire Nation to take his title as Fire Lord, he ruled for about 20 years before giving his crown to Seb. He decided to travel with Mai to the Sun Warriors to aid in the rehabilitation of the dragon population, where they’re still working on recovering the dragon population today.
Iroh
He simply runs a tea shop located in Harbor Town.
Azula
She is arrested and placed in a maximum-security prison, where she still is now.
Kuei
Kuei returns to the Earth Kingdomlong enough to raise and prepare his child to rule. Jakob becomes monarch of the Earth Kingdom when Kuei renounces the crown and returns to traveling the world with Bosco.
Arnook †
He leaves the Northern Water Tribe to help reconstruct the South due to internal rivalries. After two successions, the current leader is an unknown male chief. Arnook eventually passes away from old age.
Hakoda
After helping Arnook and Northerners to repopulate and rebuild the Southern Water Tribe, he hands over the chieftaincy to Kaito and retires to a small Water Tribe village to live with his girlfriend.
Bumi
It is unknown whatever happened to Bumi. After the liberation of Ba Sing Se, he seemingly disappeared. Earthbender legend has it that he somehow still lives.
Reposted from Enjin. Originally posted by Kyonga.