The Avatar: The Last Airbender animated series birthed an entirely new franchise that has a legion of devoted fans. While not every aspect has been great, such as the terrible live-action movie, most of it has been pure gold, including most of the comic books.
While the TV series ended in 2008, the comics did a superb job of expanding on the overall universe. This has included bringing in a variety of new characters that only appeared in those same comics books. Not all of them were great, but they still added to the mythology. That being said, there were a lot of amazing characters that fans hope find a place in any upcoming series and movies.
Satoru
Born in the Fire Nation, Satoru's parents were Ozai loyalists who continued to serve him long after his defeat by Aang. Not agreeing with their world view, Satoru ran to Ba Sing Se where he started working with his uncle.
A non-bender, Satoru grew to become a key part of his uncle's business, Earthen Fire Industries. Satoru was also a huge fan of Team Avatar, and became an important player in the rebuilding process after the Hundred Year War.
Maliq
The period of upheaval created by the Hundred Year War was especially devastating on the Air Nomads as well as the Southern Water Tribe. While the Air Nomads were utterly devastated, the Southern Water Tribe was left with virtually nothing.
After the end of the war, Maliq traveled from the Northern Water Tribe to the south. As an engineer and architect, he was uniquely suited to help guide the massive Southern Reconstruction Project, though his plans were more nefarious than they first seemed.
The First Group Of Metal Bending Students
Toph Beifong made her debut in the sixth episode of Book Two of Avatar: The Last Airbender. This acerbic young girl was blind, which her rich parents used as an excuse to coddle her. In truth, she was one of the most powerful earthbenders of all time.
In addition to that, Toph was also the originator of metalbending, an offshoot of earthbending. Once Ozai was defeated, Toph opened a metalbending school. Her first group of students only appeared in the comics, and were certainly a unique bunch.
Mother Of Faces
Both Avatar: The Last Airbender and The Legend of Korra are overflowing with incredible battles and action scenes. At the same time, the core of this world is its spirituality. The spirits that inhabit parts of this world come up frequently, and are a big part of the story.
One of the most powerful, not to mention ancient, spirits of them all is the Mother of Faces. She quite literally gives faces to living beings, including both plants and animals. It's an odd thing to be in charge of but someone has to do it.
Liling
While people like Satoru advocated for cooperation between benders and non-benders in the wake of the Hundred Year War, not everyone felt the same way. There were people on both sides who felt their group was superior.
Liling was one such person. An earthbender and businesswoman in competition with Earthen Fire Industries, she was also a secret bender supremacist. Liling's goal was to push all of the non-benders out of her hometown.
General Old Iron
When it comes to dealing with the spirits, it quickly becomes apparent that they get offended quite easily. They should have a lot thicker metaphorical skins, but that has been proven time and time again to not be the case.
General Old Iron was a spirit whose job was to protect Lady Tienhai. He has been on a couple of rampages over the years, one ended by Avatar Yangchen and the other ended by Avatar Aang. He's not the biggest fan of people.
Lady Tienhai
It's always worth noting that not all spirits are as grumpy as General Old Iron. Some of them are generally nice and actually helpful. At the very least, they don't try to destroy humanity at the drop of a hat.
Lady Tienhai, who the General protected, was the guardian of a city. She started turning into a human one day a year to enjoy that city, and eventually died in that form. It was her death that inspired one of Old Iron's rampages.
Malina
In addition to Maliq, his sister Malina was also sent to help the Southern Water Tribe. Like her brother, Malina was a skilled engineer and architect as well as a waterbender, though she spent most of her life in the Earth Kingdom.
Malina was the one who revealed that the Northern Water Tribe was actually trying to colonize the Southern Water Tribe's territory and take their resources for themselves. She sided with the Southerners, and worked to improve their standard of living.
Kiyi, Zuko's Half-Sister
All of the main characters of Avatar: The Last Airbender went through incredible journeys throughout the series. But Zuko might have gone through the biggest changes, transitioning from being Aang's worst enemy to being one of his closest allies and friends.
A big part of his story was his mother, Ursa, being banished by his father, Lord Ozai. Zuko and Ursa eventually reconnected which is when he met his half-sister Kiyi. This relationship showed a softer side of Zuko, one that deserves further exploration.
Noren/Ikem
Before Ursa was forced to marry Ozai, she was briefly engaged to a man named Ikem. They had known each other for years and losing her absolutely devastated him. He asked the Mother of Faces for a new face and became a man named Noren.
After Ursa's banishment, they reconnected. She also got a new face and became Noriko, then got married and had Kiyi. While this all filled in some of the blanks as to what happened to Ursa, there is still some story to tell in their lives and Zuko's.