Gaia

Gaia comes almost first. In Hesiod there is Chaos, and then Gaia — not made by anyone, not born of anyone, simply there as the broad-breasted ground on which everything else can stand. She produced Ouranos, the sky, by herself, to cover her on all sides, and then took him as a husband. Her children are the twelve Titans, the three Cyclopes and the three Hundred-Handers.

She is also the reason both of the first two rulers of the cosmos fell. When Ouranos crushed her children back inside her, Gaia made the adamant sickle and found a son willing to use it. When Kronos then jailed the same children, she helped Rhea hide Zeus and told him where his siblings were. The pattern is consistent and worth stating plainly: Gaia is not on a side, she is on the side of whatever has been buried.

That does not make her benign. After the Titans lost, she turned on Zeus too, producing Typhon — the last and worst thing the Olympians ever had to fight — and, in later sources, the Giants who besieged Olympus. Her prophecies drive most of the succession myths, including the warning that kept Zeus from fathering a son by Thetis, which is why Achilles was born mortal.

The Greeks swore their most binding oaths on her, and no myth records her being defeated, imprisoned or overthrown. Every other power in the theogony has a story about being beaten. Gaia has stories about outlasting.