Katara is a beautiful young female Water Bender, born and raised in the Southern Water Tribe by her grandmother, Kanna, alongside her big brother Sokka as well as the deuteragonist of Avatar: The Last Air Bender and one of the supporting characters in The Legend of Korra. Katara was not only a Water Bender, but the last and only one capable of the art in her tribe. As a child, she lived a peaceful life with her family's love, until she lost her mother in a Fire Nation raid. Years after this tragedy, during her teenage years, she and her older brother discovered the young air nomad avatar named Aang, who had been encased for one hundred years within a sphere of ice. In need of a water bending teacher, the two siblings and Aang left the South Pole for the Northern Water Tribe. Katara and her older brother Sokka eventually became close friends of Aang, and after their journey to the North Pole, continued to travel with him across the world as he mastered the remaining elements, earth and fire. The siblings' assistance helped Aang halt the Fire Nation's ambitions of world domination, ending the century-long war, and finally restoring balance to the world.
70 years after the war, Katara is now a widow, a mother, and a grandmother but she still is a water bending teacher to the new avatar named Korra.
When Katara was a young girl, her biological mother was killed, murdered, and slain in a Fire Nation raid. This event had a tremendous impact on Katara's life and personality and arguably shaped her into the person she became. She was emotionally driven, involving herself completely in the heartache and needs of those around her. Placing her whole heart in the affairs of others, as well as bearing her own heartache, she was often easily reduced to tears. According to her older brother Sokka, Katara largely prevented their family from falling apart and took on many responsibilities to the point where she filled the void left by their mother (so much that he pictured her in place of his biological mother). As such, Katara had a maternal personality and often acted as a motherly figure to the group, something that often irritated the rebellious Toph Bei Fong. Her loss was also part of what drove her in her fight against the Fire Nation, although she did not exhibit as much outward prejudice as her older brother. She was also a bit of a stickler for morality, even to the point of causing both Sokka and Aang to faint from shock when she stated she wanted to pull a scam, as she had berated Toph for scamming people. According to Sokka, she was an optimist.
She had a soft spot for children. When aiding in baby Hope's birth, she stated that she helped her grandmother deliver many babies in their tribe, and in Jang Hui, she gave a portion of her food to a little boy. She even went as far as to care for and defend Tom-Tom, Mai's little brother, despite the fact that he was from the Fire Nation and that everyone else, with the exception of Aang, was distrustful of him for it. Katara was caring and compassionate, and was often marked by a fierce determination to aid others. She stated herself that she would never turn away from people who need her help. Katara was even willing to defend Fire Nation civilians such as when she helped the village of Jang Hui and when she fought Hama, who was from the Southern Water Tribe, to protect the Fire Nation village she was living in. This strong desire often frustrated others, particularly her older brother Sokka.
Katara was portrayed as the most mature member of the group, rarely taking part in Sokka and Aang's goofy pranks and Toph's less silly ones, though she did have a sense of humor. Katara was described as being motherly by Toph and Sokka. While the team traveled through the Si Wong Desert, Katara was able to hold the group together in its most desperate moments.
On the other hand, Katara could be overly domineering. For all her kindness and compassion, she was sometimes self-righteous, had a nasty behavior, and could be fierce when provoked. With lack of sleep, this side of her can quickly become more apparent. She was also set in her ideals and frequently refused to relent on her views in the face of opposition. Combined with her strong sense of compassion, this gave her a strong sense of justice and she would run headlong into often dangerous situations to help others, which was best illustrated at the prison rig and at Jang Hui. Her short temper had frequently clashed with others; she showed open, but short-lived, jealousy of Aang's talent, and was frequently perturbed by Toph's confrontational and rebellious nature.
Despite being one of the more compassionate members of the group, Katara was one of the least willing to let go of a grudge, especially against those who she felt had betrayed her trust. She held a considerable grudge against those who had threatened Aang, as Zuko had, or done things she considered morally wrong, like Jet. At the Western Air Temple she showed outright hostility toward Zuko and threatened to kill him if he slipped back to his old ways. Upon her re-encounter with Jet, Katara reacted hostilely at the mere sight of him, and she was harsh and unforgiving of Zuko even long after he had joined Team Avatar and gained the trust of everybody else. However, this could be because Zuko's betrayal of her at Ba Sing Se was far more personal than his betrayal of anybody else. For a while, she was also argumentative with her biological father because she felt that he had abandoned her and Sokka when he left to fight in the war. However, Katara was sometimes willing to give people second chances; with much reluctance, she allowed Jet to guide Team Avatar to Appa, and she appeared to be saddened by his death. Also, she offered to try and heal Zuko's scar when they were bitter enemies. Eventually, even after his betrayal, Katara decided to forgive him, embracing him as a friend, after he helped her find the man who killed her biological mother.
Katara was marked by a fierce desire to learn water bending, viewing it as a part of her and her culture that needed to be expressed. She also may have viewed it as a hope for rebuilding her tribe. Her enthusiasm for water bending caused her to constantly train herself in the art, and when she finally found a master to teach her formally, she became overjoyed. Having quickly advanced under the tutelage of Master Pakku, he stated that Katara accomplished this due to her fierce determination, passion and hard work.
Sokka told Toph that Katara could be a pain and would get "involved and in-your-business". Even so, Katara was understanding of other people's privacy. This was best demonstrated when Katara continually scolded her older brother Sokka for snooping around Hama's inn and rummaging through her personal belongings.