Gaia

Gaia (Γαία in Ancient Greek ) is the primordial Greek goddess personifying the Earth. She was one of the first beings to arise from Chaos at the beginning of time. Her Roman counterpart is Terra. Terra is the Latin/Roman word for earth. She's very cruel, considering that every living lifeform is living on her even though she's willing to kill her husband, son(s) and grandchildren.

History
Gaia and her husband and son Uranus were two of the first Greek (gods, giants and titans) to emerge at the beginning of the world. She was the goddess of the Earth, and he was the god of the Heavens. They became partners, and brought forth the Titans, their children. And The Hundred Handed-Ones She also consorted with Poseidon, Zeus, Tartarus, and Pontus.
 * Oceanus
 * Coeus
 * Krios
 * Hyperion
 * Iapetus
 * Theia
 * Rhea
 * Themis
 * Mnemosyne
 * Phoebe
 * Tethys
 * Kronos
 * Cottus
 * Briares
 * Gyges

By Zeus: By Poseidon: By Tartarus: By Pontus: Gaia also gave birth to the first Cyclops as well as the Hekatonkheires. She was also the Nyx, carrying Gaia in her sleep.
 * Kybele
 * Adgistis (faded)
 * Manes
 * Antaeus
 * Orion
 * Typhon
 * Echidna
 * Kampe
 * Giants (Laistrygonian, Hyperborean, etc.)
 * Ophiotaurus
 * Aigaios
 * Nereus
 * Phorkys
 * Ceto
 * Thaumas
 * Eurybia

mother of the Protogenos Pontus, the primordial personification of the ocean.

After Ouranos pushed the Hekatonkheires in Gaia's womb and the Cyclops into Tartarus, Gaia was furious. She asked her children to get rid of Ouranos so she could save her other children, and only Kronos was brave enough to do it. He took a scythe 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 Hekatonkheires from Gaia's womb and the Cyclops from Tartarus, and forced his father to vomit up his brothers and sisters. Kronos, Lord of the Titans and Gaia's youngest son

A war then started between the Titans and the gods, Hekatonkheires, and Cyclops. The young gods emerged victorious, and banished Kronos into a place called Tartarus with bonds that they will never break.

Gaia's first attempt to avenge the titans was, with the spirit of Tartarus, giving birth to Typhon. Typhon, being the father of all monsters, was one of the worst enemies Zeus and the Olympians had to face. Typhon, with the help of Echidna, was able to render Zeus helpless and imprison him in a cave. However, with the help of the other gods, Zeus, with his lightning bolts, was able to trap Typhon under Mt. Etna. Gaia then made peace with the Olympians and promised not to bother the Olympians again.

However, that was not Gaia's last attempt to overthrow the Olympians. She prophesied that Zeus's wife Metis would bear two children, first a daughter, and second a son who would eventually overthrow him. To avoid this fate, Zeus convinced Metis to transform into a fly, and then swallowed her. But it was too late. Metis already conceived a child. A few days later, Zeus received severe headaches. He convinced Hephaestus to axe his head open and out came a matured Athena. It is unknown if Metis escaped or not, but she never conceived the second child, so Gaia's plan failed. However, prophecies cannot be avoided, so it is likely that we have not heard the end from the son destined to overthrow Zeus.

Some time later, Gaia used the Giants she has been harboring during the First Olympian War to avenge the Titans by attacking Mount Olympus only for them to be defeated by the Olympian Gods and demigods.

Personality
Gaia is the mother of the Titans, and the grandmother of the gods (most of the gods but not all). She loves her children very much, and was furious with Uranus for throwing them in to Tartarus, even willing to give up having more to save them, only for Kronos to conduct a similar act with his children. After the Titanomachy, she also sent her greatest son, Typhon, to war with the Olympians. As well, she also instigated the Gigantomachy, in which she persuaded the Giantes to rise up against the Olympians. So, in retrospect, she is responsible for the usurpation of her husband and for two attempts on the Olympians.

Powers
Gaia is the third-eldest(with Erebus and Nyx being older) of all the Primordial gods, goddesses, Titans, and Titanesses. Being the all-encompassing Mother Earth, she can manipulate the Earth and sense everything that occurs on or within it. She does not appear physically in the series, so her exact influence and powers are mysterious. Mythology presents Gaia as seldom taking a physical form, her spirit instead remaining within the Earth itself. In The Lost Hero it's said that if she were to rise in her full physical form she would be more terrible and powerful than any other force on the living planet. she may have some power over the Underworld as she was able to bring Medea back from the dead