Gaia

Gaia (ガイア, Gaia) is the mother of the Titans (in addition to several other gods and creatures), the wife and consort of Uranus, the mother of Pontos and the grandmother of the gods of Olympus.

Mythological Age
Gaia was formed from Nothingness, and represents the Earth itself. After she was born, she gave birth to her son and future husband, Uranus, the representation of the sky and her physical equal. The couple had several children, the first of whom were the Titans. Gaia afterwards gave birth to the Cyclopses (creatures with only one eye) and the Hekatonkhieres (giant creatures with 100 arms and 50 heads each). However, feeling them too ugly and too powerful, Uranus trapped these last children inside Tartarus. However, he spared the Titans, which would be his undoing. Infuriated at the cruelty towards her children, Gaia created the Soma for the Titans, and encouraged her youngest son Cronus to ambush his father with Megas Drepanon to kill him. Cronus did so, but as he fell Uranus cursed Cronus to suffer the same fate, which would be fulfilled at the hands of Cronus's youngest child, Zeus, during the events of Titanomachy.

She is also the mother of Pontos. He in turn is the father of their daughter, the sea Titaness Eurybia.

At some point, Gaia ended up being sealed in the Gea Altar.

War of the Gold Saints against the Titans
The imprisoned Gaia is shown as the force behind the deity Pontos after his resurrection. Pontos in turn resurrects the Titans. Pontos, Prometheus and Mnemosyne  remain loyal to her and manipulate the Titans for her sake.

Trivia

 * Gaia can be viewed as a meddlesome deity; she often pits members of her family, immediate and extended, against one another to achieve her aims (Kronos against Uranus, Zeus against Kronos). It was at her bidding that the recurrent topos (theme) of "a father being replaced by his son" shown in many Greek myths first began (the most extreme case of this being the Oedipus complex).
 * In the original myth, only Kronos received some sort of weapon from Gaia (a scythe), as he was the only one willing to do Gaia's bidding and overthrow Uranus.
 * Gaia is not a goddess of the earth, she is actually the Earth personified. Other goddesses however are considered deities of the earth and have a share in Gaia's power, such as Rhea, Dione, and to a slightly lesser extent Demeter.
 * The marriage of Gaia and Uranus is a theme known as the hieros gaimos, a symbolic union between the Earth and the Sky, which produces offspring (the way rain fertilizes soil and causes plants to grow), and causes order and change to the world. It also usually produces a revolution or the end of an older regime, as seen with first the Titans, then the Olympians.
 * Gaia's name in other languages and other editions:
 * Ge (ancient Greek);
 * Gaia (modern Greek);
 * Gæa (ancient Latin);
 * Gea (Italian); (the Italian edition uses the modern Greek name)
 * Gea (Spanish); (the Spanish edition uses the modern Greek name, too)
 * Gaia (Portuguese)
 * Gaïa (French)