Avatar: The Last Airbender Season 3 Episode 3 : The Painted Lady
The gang arrives at Fire Nation village populated by sick and starving people. Katara wishes to stay and help them. She becomes "The Painted Lady," the town's mythical patron-saint figure, healing their sick and providing food while they sleep. She also destroys the nearby factory which pollutes their river, sparking soldiers to attack the village. Katara reveals herself after Aang finds out that she is the Painted Lady and saves them with the help of her friends. In the end, Katara is thanked by the real Painted Lady.