Katara was a waterbending master born in the Southern Water Tribe to Chief Hakoda and his wife Kya. During her childhood, she was the only waterbender living in the Southern Water Tribe. After losing her mother in a Fire Nation raid and after her warrior father left to battle against the Fire Nation in the Hundred Year War, she was raised by her paternal grandmother Kanna alongside her older brother Sokka. The murder of her mother and the later departure of her father left Katara feeling traumatized and alone.Though she was cared for by Kanna, she invariably found herself filling the mother role left behind by Kya, even to her own older brother. Katara soon took on many of the responsibilities expected of an adult and quickly became independent and strong-willed. Morally and emotionally driven, she developed a great sense of justice and compassion for others, becoming fiercely protective of those in need.

As teenagers, Katara and her brother discovered the young Air Nomad Avatar, Aang, who had been frozen in an iceberg with his bison, Appa, for a century. In need of a waterbending master, the siblings and Aang left the South Pole on a journey toward the Northern Water Tribe. After the group departed from the Northern Water Tribe, Katara became Aang's waterbending instructor, replacing Master Pakku, who had taught them during their time there. Katara and Sokka continued to travel with Aang across the world as he mastered the remaining elements: earth and fire. Katara's incredible mastery of water, compassion and sense of justice made her a formidable asset to Team Avatar. Together, the siblings helped Aang halt the Fire Nation's ambitions of world dominance, ending the century-long war and restoring balance to the world.