One of the best characters in the entire Avatar franchise is Katara, a major character on Avatar: The Last Airbender who then reappeared in a smaller role on The Legend of Korra. She was instrumental in the defeat of the Fire Nation, and helped to end the Hundred Year War.
Throughout her time on the show, Katara did many wonderful things. However, there are certainly some that soared above the rest, even going as far as to change the course of the world.
While it might have been somewhat by accident that Katara and Sokka found and freed Aang from the iceberg in the beginning of the show, Katara showed no hesitation in wanting to open it and help Aang once they realized what they were dealing with. While this does show how kind that she is, it also was the catalyst to the Hundred Year War’s eventual end.
It cannot be emphasized enough how important it was that Katara agreed to help train Aang as a waterbender. As the only waterbender in the Southern Water Tribe, the job fell on her shoulders. Despite being so inexperienced herself, she took on her duty with enthusiasm, and was a huge part in Aang being able to master waterbending as quickly as he did.
Early on in the series, the crew found a waterbending scroll that would be a huge boon to their training. Unfortunately, the pirates that had the scroll weren’t going to part with it easily. Katara ended up stealing the scroll. The situation eventually melted into a huge brawl between… everyone. While the situation put Team Avatar in danger, Katara and Aang both benefitted from using the scroll.