Thetis

Thetis is neglected somewhat here.

She was powerful enough to help Zeus, fight Giants, etc. Her son Achilles was a sort of god-son to Hera, too.

Thetis, Tethys (nurse of Hera), Tiamat, Amphitrite, Neith, Thalassa (sea personified),
and maybe a couple of others.

Thetis means "Creator" or "Creatrix" - a clue to Her long forgotten role as a mighty goddess.