Azula (Grey DeLisle) was the princess of the Fire Nation, daughter of Fire Lord Ozai and Ursa, younger sister of Zuko, older half-sister of Kiyi, paternal aunt of Izumi, and great aunt of Iroh. She was a key adversary of Team Avatar, chasing Avatar Aang and her banished brother far across the Earth Kingdomaccompanied by her two best friends at the time, Mai and Ty Lee.
A firebending prodigy, Azula was sadistic, manipulative, and obsessed with power. She was a skilled strategist who orchestrated the coup over the Earth Kingdom capital Ba Sing Se and halted the invasion on the Day of Black Sun. Flashbacks shows she was the same as a child, constantly demeaning her brother and acting out in violent and disturbing ways.
For a time, Mai and Ty Lee were her accomplices, but once they broke free of her grip, she had them imprisoned. As the day of the comet that would give Fire Lord Ozai the power to conquer all of the Nations, Azula was shocked to learn that he didn't plan on having her accompany him. She briefly melts down, but is appeased when her father says she would be named Fire Lord in his place. But soon after this, Azula's already fragile mental state began to deteriorate, resulting in her firing many of her guards and servants out of paranoia.
Just as she was about to be crowned Fire Lord, Zuko arrived with Katara, intent on stopping her once and for all. The two get into a duel and, after seeing her brother was a formidable opponent, the evil Azula tried to attack Katara with a lightning strike, which Zuko jumps in the way of. With Zuko out, Katara and Azula dueled, which ends with Katara subduing Azula and chaining her down. Realizing she had been bested, Azula had a meltdown, clearly losing what little sanity she had had left. She was then committed to a high-security mental institution to undergo treatment, for both her safety and the safety of everyone else.
- Grey DeLisle has also provided the voice of villainesses Mitzy from Johnny Bravo and Holly Graham from the video game Scooby Doo! Night of 100 Frights!
- Grey DeLisle also voiced What's New, Scooby Doo? villainesses Mademoiselle Chantal (Season Two), Verona Dempsey (Season Three), and Galina Korzhakov (Season Three).