Gaia can refer to:
- Gaia, Greek and Roman goddess
- Dr. James Lovelock's Gaia hypothesis
- The Gaia theory (science), a group of scientific theories about how life on Earth may regulate the planet's biosphere to make it more hospitable to life. This article discusses all scientific views on the subject in general, including the views of Drs. James Lovelock, Lynn Margulis, Richard Dawkins, Carl Sagan, etc.
- Gaia philosophy -- Varied philosophical views related to the Gaia theory.
- Gaia is an imaginary planet set in Isaac Asimov's Foundation Series. It is society in which all animals, planets, and even inanimate matter are telepathically connected.