Justine Larbalestier is an Australian young-adult fiction author. She is best known for the Magic or Madness trilogy: Magic or Madness, Magic Lessons and Magic's Child. She also wrote one adult non-fiction book, the Hugo-nominated The Battle of the Sexes in Science Fiction (Best Related Book, 2003), and edited another, Daughters of Earth: Feminist Science Fiction in the Twentieth Century.
Larbalestier was born and raised in Sydney, Australia. She now alternates living between Sydney and New York City.
In 2001, Justine married fellow author Scott Westerfeld. They met in New York while she was researching her PhD thesis though they have differing stories on how they met.