Gaia, also known as Gaea and Mother Nature, is the main antagonist of the Heroes of Olympus series.
She is the first being to sprung forth from the void of Chaos. She was indictly responsible for some of the major events in Percy Jackson and the Olympians and The H eroes of Olympus. Her current husband is the protogenos Tartarus, whom she conceived the Gigantes, and her former husband is Ouranos, whom she had the Titans. Her Roman counterpart is Terra or Tellus, meaning "earth" in Latin. She is also the Seven's arch-nemesis with the group as a whole.