Zuko

Zuko is a Fire Nation royal and firebending master who reigned as Fire Lord from 100 AG until his abdication in 167 AG. He is the eldest child and only son of Princess Ursa and Fire Lord Ozai. Originally the primary enemy of Team Avatar, Zuko devoted three years to trying to capture the long-lost Avatar to end his banishment and regain his honor as Crown Prince of the Fire Nation. He is recognizable by the distinctive burn scar on the left side of his face, which was given to him by his father, Ozai, shortly before his banishment as a result of an incident in which he unintentionally disrespected his father by speaking out of turn and refusing to duel him. With support from his paternal uncle, General Iroh, and after much internal struggle and turmoil, Zuko grew disillusioned and rejected Ozai and his model of the Fire Nation. He instead joined the Avatar's group to become Aang's lifelong friend and firebending mentor and was determined to end the war and restore both his and the Fire Nation's honor. While Aang defeated Ozai, Zuko, with the help of Katara, defeated his younger sister, Princess Azula, and took his place as Fire Lord, declaring the end of the Hundred Year War and the start of a new era of love and peace.