Azula

Azula was a princess of the Fire Nation, daughter of Fire Lord Ozai and Ursa, younger sister of Zuko, and older half-sister of Kiyi. She was a key adversary of Team Avatar, chasing Avatar Aang and her banished brother far across the Earth Kingdom accompanied by her then two best friends, Mai and Ty Lee. A firebending prodigy, Azula was manipulative and obsessed with power. She was a skilled strategist who orchestrated the coup of the Earth Kingdom capital, Ba Sing Se, and halted the invasion on the Day of Black Sun.