Gaia

Gaia (Γαία in Ancient Greek) is the primal Greek goddess personifying the Earth.

History
Gaia and Uranus were the first Greek gods, she was the goddess of the Earth, and he was the god of the sky. They were alone, but for each other. They became partners, and brought forth the Titans, their children.
 * 1) Oceanus
 * 2) Coeus
 * 3) Crius
 * 4) Hyperion
 * 5) Iapetus
 * 6) Theia
 * 7) Rhea
 * 8) Thermia
 * 9) Mnemosyne
 * 10) Phoebe
 * 11) Tethys
 * 12) Kronos

And the one hundred handed ones
 * 1) Cottus
 * 2) Briares
 * 3) Gyges

Gaia also gave birth to the first Cyclops.

After Uranus threw the Hecatonchires and Cyclops into Tartarus, Gaia was furious. She asked her children to get rid of Uranus so she could save her other children, and only Kronos was brave enough to do it. He took a flint sickle Gaia made, and got rid of his father.

However, Kronos didn't rescue his brothers, and Gaia was then angry with him. Gaia then prophesied that Kronos in turn was destined to be overthrown by his own son, and so the Titan attempted to avoid this fate by devouring his young. Zeus through deception by his mother Rhea, avoided this fate, and later rescues the Hecatonchires and Cyclops from Tartarus, and forced his father to vomit up his brothers and sisters.

A war then started between the Titans and the gods, Hecatonchires, and Cyclops. The young gods emerged victorious, and cut Kronos into a million pieces and tossed what was left of him into Tartarus.

The series
Gaia is mentioned in The Battle of the Labyrinth where one of her sons, Antaeus fights with Percy. While Percy is battling him, whenever his sword goes through him, sand falls out and then the earth rises up to cover him, so he is covered with dirt, when the dirt spills away, Antaeus is fine. This is due to his mother's powers.

Personality
Gaia is the mother of the Titans, and the grandmother of the gods. She loves her children very much, and was furious with Uranus for throwing them in to Tartarus.

Power
Gaia being the mother of earth can manipulate earth and can do various things with it.
 * She has the power of geokinesis- is the elemental where she can control and/or manipulate earth, such as creating an earthquake.
 * She can manipulate the weather- is the ability to manipulate the weather in all its forms for example, thunderstorms, rain, lightning, tornadoes, ect.
 * She can sense things because she can keep an eye on earth.
 * She also has the power of Force Blast, a blast of concussive force that sends targets flying through the air.